Trash Cleanup

A room is represented as a grid with N rows and M columns. The upper-left cell is (0, 0), and the lower-right cell is (N - 1, M - 1). Some cells contain trash.

Each robot starts at the upper-left cell and must finish at the lower-right cell. From its current cell, it may move only to the right or downward, and it can collect trash from every cell it visits.

Find the minimum number of robots needed to collect all trash.

The first line contains N and M separated by a space. (1 <= N, M <= 100)

Each of the next N lines contains M integers. A value of 0 means the cell is empty, and a value of 1 means the cell contains trash.

Print the minimum number of robots needed to collect all trash.