Поменять местами строки матрицы, в которых расположены максимум и минимум - VB

Sub matritsa() 
 
Cells.Clear
Dim a(20, 20) As Integer
Dim i, n As Integer
n = Val(InputBox("Введите размерность матрицы"))
For i = 1 To n
For j = 1 To n
 a(i, j) = Int((-100 * Rnd) + 100)
Cells(i, j) = a(i, j)
 Next j
 Next i
For i = 1 To n
For j = 1 To n
 max = a(i, j)
 min = a(i, j)
 If a(i, j) > max Then max = a(i, j)
 If a(i, j) < min Then min = a(i, j)
 Next j
 Next i
 
For i = 1 To n
For j = 1 To n
x = a(max, j)
a(max, j) = a(min, j)
a(min, j) = x
Next j
Next i
End Sub