// Jocul Flip
#include <iostream>
#include <fstream>
#include <cmath>

using namespace std;

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

int a[100][100], n, m, s[20], maxi;

void calcul()
{
    int Su = 0;
    for(int j=1;j<=m;j++)
    {
        int sumc = 0;
        for(int i=1;i<=n;i++)
            if(a[i][j] > 0)
            sumc = sumc + a[i][j];
        sumc = abs(sumc);
        Su += sumc;
        maxi = max(maxi, Su);
    }

}

int main()
{
    int i, j;

    in>>n>>m;

    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            in>>a[i][j];



    calcul();

    out<<maxi;
    return 0;
}