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

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

const int N=20;

int a[N][N],n,m,Snl[N],Spl[N],Snc[N],Spc[N];
int main()
{
    int i,j,S=0;
    in>>n>>m;
    for(i=1; i<=n; i++)
    {
        for(j=1; j<=m; j++)
        {
            in>>a[i][j];
            if(a[i][j]>0)
                Spl[i]=Spl[i]+a[i][j];
            else
                Snl[i]=Snl[i]+a[i][j];
        }
    }
    for(i=1; i<=n; i++)
        if(Snl[i]>Spl[i])
        {
            for(j=1; j<=m; j++)
                a[i][j]=-a[i][j];
        }
    for(j=1; j<=m; j++)
    {
        for(i=1; i<=n; i++)
        {
            if(a[i][j]>0)
                Spc[j]=Spc[j]+a[i][j];
            else
                Snc[j]=Snc[j]+a[i][j];
        }
        if(Snc[j]>Spc[j])
            S=S-Snc[j];
        else
            S=S+Spc[j];
    }
    out<<S;
    return 0;
}