#include<iostream>
#include<fstream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<vector>
#include<map>
#include<cstring>
#include<cstdlib>
using namespace std;

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

int n,m,a[17][17],st[20],sumamax;

inline void Citire()
{
    int i,j;
    fin>>n>>m;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            fin>>a[i][j];
}

inline void Analizeaza(int k)
{
    int i,j,sur;
    int mat[17][17];
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            mat[i][j]=a[i][j];
    for (i=1;i<=k;i++)
        for (j=1;j<=m;j++)
            mat[st[i]][j]=-mat[st[i]][j];
    for (i=1;i<=m;i++)
            {
                sur=0;
                for (j=1;j<=n;j++)
                    sur+=mat[j][i];
                if (sur<0)
                    for (j=1;j<=n;j++)
                        mat[j][i]=-mat[j][i];
            }
    sur=0;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            sur+=mat[i][j];
    if (sur>sumamax) sumamax=sur;
}


inline void Back()
{
    int i,lim,aux,j,lung;
    lim=(1<<n)-1;
    for (i=1;i<=lim;i++)
        {
            aux=i;
            j=1;lung=0;
            while (aux)
                {
                    if (aux%2==1)
                       st[++lung]=j;
                    j++;
                    aux>>=1;
                }
            Analizeaza(lung);
        }
}

inline void Afisare()
{
    fout<<sumamax<<"\n";
}

int main()
{
    Citire();
    Back();
    Afisare();
    return 0;
}