单项选择题

下列程序段的执行结果为 ______。
Dim m(3，3)As Integer
Dim i As Integer
Dim j As Integer
Dim x As Integer
For i=1 To 3
m(i，i)=i
Next
For i=0 To 3
For j=0 To 3
x=x+m(i，j)
Next
Next
Print x