I have a matrix in cells A1 across to D1 and A1 down to a4 (16 cells)

It looks like this:
A B C D
1 5 6 7
2 8 M N O
3 9 P Q R
4 10 S T U

If i enter "6" in cell m1, and "9" into cell m2, i want resultant intersect
"Q" to appear in m3

If i enter "7" in cell m1, and "10" into cell m2, i want resultant intersect
"U" to appear in m3

Thanks very much