#include <iostream>
#include <fstream>

using namespace std;

ifstream in("flip.in");
ofstream out("flip.out");

int main()
{
    int N, M, s=0;
    in >> N >> M;
    int matrice[N][M];
    for (int i=0; i<N; i++)
    {
        for (int j=0; j<M; j++)
        {
            in >> matrice[i][j];
            if (matrice[i][j]>0)
                s=s+matrice[i][j];
        }
    }
    out << s;
}