#include <iostream>
#include <fstream>
using namespace std;
int N, M, x, s;
int main()
{
    ifstream f("flip.in");
    ofstream g("flip.out");
    f >> N >> M;
    for (int i = 1; i <= N * M; i++)
            {
                f >> x;
                if (x > 0)
                    s += x;
            }
    g << s;
    f.close();
    g.close();
    return 0;
}