#include<stdio.h.
int main() {
    int m, n, price;
    long long total = 0;
    if (scanf("%d %d", &m, &n) != 2)
return 0;
    if (m < 0 || n < 0) {
        printf("Invalad Input\n");
        return 0;
    }
    for (int i = 0; i < m * n; i++) {
        if (scanf("%d", &price) != 1)
return 0;
        if (price < 0) {
            printf("Invalid Input\n");
            return 0;
        }
        total += price ;
    }
    printf("%lld\n", total);
    return 0;
}