#include <iostream>
#include<fstream>
using namespace std;
int v[257],n;
int main()
{
    ifstream in("flip.in");
    ofstream out("flip.out");
    int i,n,m,a;
    long long s;
    in>>n>>m;
    a=n*m;
    s=0;
    for(i=1;i<=a;i++)
    {
        in>>v[i];
    }
    for(i=1;i<=a;i++)
    {
        if(v[i]>0)
        s=s+v[i];
    }
    out<<s<<" ";
    in.close();
    out.close();
}