Недоступен из-за своего уровня защиты - C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;
using Microsoft.VisualBasic;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        public struct Students
        {
            string fio, math, rus, fiz;
        }
 
        Students[] str = new Students[50];
        int i, n, r;
        //var fileSW = new StreamWriter();
 
        public void button1_Click(object sender, EventArgs e)
        {
            dataGridView2.Rows.Clear();
            double SrClass = 0, SumClass = 0;
            string S;
            for (int i = 0; i <= n; i++)
            {
                int Sum = 0; double Sr = 0;
                Sum = Convert.ToInt32(str[i]).math + Convert.ToInt32(str[i]).rus + Convert.ToInt32(str[i]).fiz;
                Sr = Sum / 3;
                S &= Convert.ToString(str[i].fio + " " & Sum + " / " + Sr + "\n");
                SumClass += Sr;
                SrClass = SumClass / (n + 1);
            }
 
            r = 0;
            for (int i = 0; i <= dataGridView1.RowCount - 1; i++)
            {
                int Sum = 0; double Sr = 0;
                Sum = str[i].math + +str[i].rus + +str[i].fiz;
                Sr = Sum / 3;
                if (Sr > SrClass)
                {
                    dataGridView1.Rows.Add();
                    dataGridView1.Rows[r].Cells[0].Value = i + 1;
                    dataGridView1.Rows[r].Cells[0].Value = str[i].fio;
                    dataGridView1.Rows[r].Cells[0].Value = str[i].math;
                    dataGridView1.Rows[r].Cells[0].Value = str[i].rus;
                    dataGridView1.Rows[r].Cells[0].Value = str[i].fiz;
                    r++;
                }
            }
            MessageBox.Show("Сумма и средний балл:" + "/n" + S + "/n" + "Средняя оценка в классе:" + " " + Math.Round(SrClass, 1), "Ответ");
        }
 
        public void Form1_Load(object sender, EventArgs e)
        {
            dataGridView1.Rows.Clear(); dataGridView2.Rows.Clear();
            var settingsfile = new System.IO.StreamReader("settings.txt");
            var strSettings = settingsfile.ReadLine();
            if (strSettings == "")
            {
                MessageBox.Show("В settings.txt не прописан файл!", "Упс!");
                settingsfile.Close();
                if (openFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    var fileSR = new System.IO.StreamReader(openFileDialog1.FileName);
                    var settingsfileNew = new System.IO.StreamWriter("settings.txt");
                    settingsfileNew.WriteLine(System.IO.Path.GetFileName(openFileDialog1.FileName)); // Запись в файл имени файла
                    while (!fileSR.EndOfStream)
                    {
                        str[n].fio = fileSR.ReadLine();
                        str[n].math = fileSR.ReadLine();
                        str[n].rus = fileSR.ReadLine();
                        str[n].fiz = fileSR.ReadLine();
                        n++;
                    }
                    n--;
                    fileSR.Close(); settingsfileNew.Close();
                }
            }
            else
            {
                var fileSR = new System.IO.StreamReader(strSettings);
                while (!fileSR.EndOfStream)
                {
                    str[n].fio = fileSR.ReadLine();
                    str[n].math = fileSR.ReadLine();
                    str[n].rus = fileSR.ReadLine();
                    str[n].fiz = fileSR.ReadLine();
                    n++;
                }
                n--;
                fileSR.Close(); settingsfile.Close();
            }
 
            for (i = 0; i <= n; i++)
            {
                dataGridView1.Rows.Add();
                dataGridView1.Rows[i].Cells[0].Value = i + 1;
                dataGridView1.Rows[i].Cells[0].Value = str[i].fio;
                dataGridView1.Rows[i].Cells[0].Value = str[i].math;
                dataGridView1.Rows[i].Cells[0].Value = str[i].rus;
                dataGridView1.Rows[i].Cells[0].Value = str[i].fiz;
            }
        }
    }
}

Public Class Form1
    Private Structure Students
        Dim fio As String
        Dim math, rus, fiz As String
    End Structure
 
    Dim str(50) As Students
    Dim i, n, r As Integer
    Dim fileSW As IO.StreamWriter
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        DataGridView2.Rows.Clear()
        Dim SrClass As Single = 0, SumClass As Single = 0
        Dim S As String
        For Me.i = 0 To n
            Dim Sum As Integer = 0, Sr As Single = 0
            Sum = str(i).math + +str(i).rus + +str(i).fiz
            Sr = Sum / 3
            S &= CStr(str(i).fio & Space(1) & Sum & " / " & Sr & vbCrLf)
            SumClass += Sr
            SrClass = SumClass / (n + 1)
        Next
 
        r = 0
        For Me.i = 0 To DataGridView1.RowCount - 1
            Dim Sum As Integer = 0, Sr As Single = 0
            Sum = str(i).math + +str(i).rus + +str(i).fiz
            Sr = Sum / 3
            If Sr > SrClass Then
                DataGridView2.Rows.Add()
                DataGridView2.Rows(r).Cells(0).Value = i + 1
                DataGridView2.Rows(r).Cells(1).Value = str(i).fio
                DataGridView2.Rows(r).Cells(2).Value = str(i).math
                DataGridView2.Rows(r).Cells(3).Value = str(i).rus
                DataGridView2.Rows(r).Cells(4).Value = str(i).fiz
                r += 1
            End If
        Next i
        MsgBox("Сумма и средний балл:" & vbCrLf & S & vbCrLf & "Средняя оценка в классе:" & Space(1) & Math.Round(SrClass, 1))
    End Sub
 
    Private Sub ВыходToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ВыходToolStripMenuItem.Click
        End
    End Sub
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        DataGridView1.Rows.Clear() : DataGridView2.Rows.Clear()
        Dim settingsfile = New System.IO.StreamReader("settings.txt")
        Dim strSettings = settingsfile.ReadLine()
        If strSettings = "" Then
            MsgBox("В settings.txt не прописан файл!")
            settingsfile.Close()
            If OpenFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
                Dim fileSR As New System.IO.StreamReader(OpenFileDialog1.FileName)
                Dim settingsfileNew = New System.IO.StreamWriter("settings.txt")
                settingsfileNew.WriteLine(System.IO.Path.GetFileName(OpenFileDialog1.FileName)) 'запись в файл имени файла
                While (Not fileSR.EndOfStream)
                    str(n).fio = fileSR.ReadLine()
                    str(n).math = fileSR.ReadLine()
                    str(n).rus = fileSR.ReadLine()
                    str(n).fiz = fileSR.ReadLine()
                    n += 1
                End While
                n -= 1
                fileSR.Close() : settingsfileNew.Close()
            End If
        Else
            Dim fileSR As New System.IO.StreamReader(strSettings)
            While (Not fileSR.EndOfStream)
                str(n).fio = fileSR.ReadLine()
                str(n).math = fileSR.ReadLine()
                str(n).rus = fileSR.ReadLine()
                str(n).fiz = fileSR.ReadLine()
                n += 1
            End While
            n -= 1
            fileSR.Close() : settingsfile.Close()
        End If
 
        For Me.i = 0 To n
            DataGridView1.Rows.Add()
            DataGridView1.Rows(i).Cells(0).Value = i + 1
            DataGridView1.Rows(i).Cells(1).Value = str(i).fio
            DataGridView1.Rows(i).Cells(2).Value = str(i).math
            DataGridView1.Rows(i).Cells(3).Value = str(i).rus
            DataGridView1.Rows(i).Cells(4).Value = str(i).fiz
        Next i
    End Sub
 
    Private Sub ОткрытьToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ОткрытьToolStripMenuItem.Click
        DataGridView1.Rows.Clear() : DataGridView2.Rows.Clear()
        Dim settingsfile = New System.IO.StreamWriter("settings.txt")
        If OpenFileDialog1.ShowDialog() = System.Windows.Forms.DialogResult.OK Then
            Dim fileSR As New System.IO.StreamReader(OpenFileDialog1.FileName)
            settingsfile.WriteLine(System.IO.Path.GetFileName(OpenFileDialog1.FileName))
            n = 0
            While (Not fileSR.EndOfStream)
                str(n).fio = fileSR.ReadLine()
                str(n).math = fileSR.ReadLine()
                str(n).rus = fileSR.ReadLine()
                str(n).fiz = fileSR.ReadLine()
                n += 1
            End While
            n -= 1
            fileSR.Close() : settingsfile.Close()
        End If
 
        For Me.i = 0 To n
            DataGridView1.Rows.Add()
            DataGridView1.Rows(i).Cells(0).Value = i + 1
            DataGridView1.Rows(i).Cells(1).Value = str(i).fio
            DataGridView1.Rows(i).Cells(2).Value = str(i).math
            DataGridView1.Rows(i).Cells(3).Value = str(i).rus
            DataGridView1.Rows(i).Cells(4).Value = str(i).fiz
        Next i
    End Sub
 
    Private Sub ТитульныйЛистToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ТитульныйЛистToolStripMenuItem.Click
        Form2.Show()
    End Sub
End Class