#include <iostream>
#include <fstream>
using namespace std;

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

int main()
{
    int n, m, A[17][17];
    long long s=0;
    fin >> n >> m;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
    {
            fin >> A[i][j];
            if(A[i][j]>0)
                s+=A[i][j];
    }
    fout << s;
    return 0;
}