求大佬解决一个VB问题

Private Sub Command1_Click()

Dim m As Integer, n As Integer

m = InputBox("请输入矩阵的行数：")

n = InputBox("请输入矩阵的列数：")

Dim a(20, 20) As Integer

m1 = 1: n1 = 1: m2 = 1: n2 = 1

Randomize

For i = 1 To m

For j = 1 To n

a(i, j) = Rnd * 90 + 10

Print a(i, j);

If a(i, j) > a(m1, n1) Then m1 = i: n1 = j

If a(i, j) < a(m2, n2) Then m2 = i: n2 = j

Next j

Print

Next i

Print

Print "最大值： A(" & m1 & "," & n1 & ")=" & a(m1, n1)

Print "最小值： A(" & m2 & "," & n2 & ")=" & a(m2, n2)

End Sub