#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("flip.in");
ofstream fout("flip.out");
int main(void)
{
    int a , b;
    fin >> a >> b;
    int m[21][21];
    int i , j , x , y = 0;
    for(i=1;i<=a;i++)
    {
        for(j=1;j<=b;j++)
        {
            fin >> m[i][j];
            if(m[i][j]>0)y=y+m[i][j];
        }
    }
    fout << y;
}