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

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

int a[17][17];

int main()
{
    short m, n;
    is >> m >> n;
    long suma = 0;
    for ( int i = 1; i <= m; i++ )
        for ( int j = 1; j <= n; j++ )
        {
            is >> a[i][j];
            if ( a[i][j] > 0 )
                suma += a[i][j];
        }
    os << suma;
    is.close();
    os.close();
    return 0;
}