#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
#define For(i,a,b) for(i=a;i<=b;i++)
ifstream f("flip.in");
ofstream g("flip.out");
int main()
{
 int n,m,i,j,smax=0,a[100][100],S[100]={0},s=0,so[100]={0};
 f>>n>>m;
For(i,0,n-1) For(j,0,m-1)
{
    f>>a[i][j];
    S[j]+=a[i][j];
    so[i]+=a[i][j];
}

    for(i=0;i<(1<<m);i++)
    {
        int k=i;
        For(j,0,m-1)
        {   int p=1;
            if(i&(1<<j))
                p=-1;
            s+=p*S[j];
            For(j,0,n-1) a[j][k]*=p;
        }

        if(s>smax) smax=s;
        s=0;
    }
    smax=0;
For(i,0,n-1)
{
    if(so[i]<0)
    For(j,0,m-1) a[i][j]*=-1;
}
For(i,0,n-1) For(j,0,m-1)
smax+=a[i][j];

g<<smax;

}