Класс Календарь - C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace Calendar
{
class Calendar
{
public static int Day (int n)
{
for (int i = n; i >= 1; i--)
if (i % 7 == 0) return n-i;
return 0;
}
public static void Season(int n)
{
if ((n <= 59 && n>=1) || (n <= 365 && n > 334)) Console.WriteLine("It's Winter");
else if (n > 90 && n <= 181) Console.WriteLine("It's Spring");
else if (n > 181 && n <= 273) Console.WriteLine("It's Summer");
else if (n > 273 && n <= 365) Console.WriteLine("It's Autumn");
}
public static void Month(int n)
{
if (n <= 31 && n >= 1) Console.WriteLine("It's January");
if (n <= 59 && n > 31) Console.WriteLine("It's February");
if (n <= 90 && n > 59) Console.WriteLine("It's March");
if (n <= 120 && n > 90) Console.WriteLine("It's April");
if (n <= 151 && n > 120) Console.WriteLine("It's May");
if (n <= 181 && n > 151) Console.WriteLine("June");
if (n <= 212 && n > 181) Console.WriteLine("July");
if (n <= 243 && n > 212) Console.WriteLine("August");
if (n <= 273 && n > 243) Console.WriteLine("September");
if (n <= 304 && n > 273) Console.WriteLine("October");
if (n <= 334 && n > 304) Console.WriteLine("November");
if (n <= 365 && n > 334) Console.WriteLine("December");
 
}

}
class Program
{
static void Main(string[] args)
{
Calendar ocb = new Calendar();
int s = Int32.Parse(Console.ReadLine());
Console.WriteLine(Calendar.Day(s));
Console.WriteLine(Calendar.Month(s)); // здесь пишет ошибку - Argument 1 : cannot convert from "void" to "bool".

Console.ReadKey();
}
}
}