#include <stdio.h>

int main() {
    int n, m, sum = 0;
    scanf("%d %d", &n, &m);
    int arr[n][m];
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            scanf("%d", &arr[i][j]);
            if (arr[i][j] > 0)
                sum += arr[i][j];
        }
    }
    printf("%d", sum);
    return 0;
}