#include <fstream>
using namespace std;
ifstream in("flip.in");
ofstream out("flip.out");
int main() {
    int n,m,S=0,x;
    in>>n>>m;
    for(int i=1;i<=n;i++)
        for(int k=1;k<=m;k++)
    {
        in>>x;if(x>0)S+=x;
    }
    out<<S;
    return 0;
}