Given an M-by-N integer matrix, compute the maximum column sum.
[Example]
For example, if the input is a 3-by-4 matrix containing
3 2 4 5
2 8 3 7
3 1 5 6
The maximum column sum is 18 (=5+7+6).
The first line of the input contains two integers M and N indicating the size of the integer matrix (M for row and N for column, 0 < M, N< 10).
Next M lines list the elements of the matrix row by row. All elements are integers.
The output contains an integer indicating the maximum column sum. There is NO newline character at the end of line.