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