#include<fstream>
using namespace std;
int main ()
{   ifstream f("flip.in");
    ofstream g("flip.out");
    int N,M,i,j,s=0;
    f>>N>>M;
    int a[N][M];
    for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)
        f>>a[i][j];
    for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)
            if (a[i][j]>0)
            s=s+a[i][j];

    g<<s;
    f.close();
    g.close();

}