#include <bits/stdc++.h>
using namespace std;

ifstream fin("flip.in");
ofstream fout("flip.out");
int n,m,i,j,a[17][17],sumax=INT_MIN;
bool linie[17]; //pastrez liniile pe care le iau;

void back(int val)
{
   if(val > n) //daca am trecut prin toate liniile
   {
       int crnt_sum = 0;
       int s[17]={};

       for(i=1; i<=n; i++)
            for(j=1; j<=m; j++)
            {
                if(linie[i])
                       a[i][j]*=-1; //flip-uit;

                s[j]+=a[i][j];
            }
        for(j=1; j<=m; j++)
        {
            if(s[j] < 0) s[j]*=-1; //flip-uim toata coloana

            crnt_sum+=s[j]; //suma totala a matricei, prin coloane
        }

        if(crnt_sum > sumax) sumax = crnt_sum;

   }

   else
   {
        linie[val] = 1; // a fost aleasa sa fie flip-uita
        back(val+1);

        linie[val] = 0; //nu va fi flip-uita
        back(val+1);

   }
}
int main()
{
    fin>>n>>m;

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

    back(1);

    fout<<sumax;
    return 0;
}