#include <iostream>
#include<fstream>

using namespace std;


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


short unsigned int n, m, i, j, poz = 1, c;


int a[17][17], s, aux;


bool ok = true;


int main()
{
    
    fin>>n>>m;
    
    for(i = 1; i<=n; i++)
    {
        for(j = 1; j<=m; j++)
        {
            fin>>a[i][j];
        }
    }
    
    for(j = 1; j<=m; j++)
    {
        s = s+ a[1][j];
    }
    
    for(i = 2; i<=n; i++)
    {
        for(j = 1; j<=m; j++)
        {
            aux = aux+a[i][j];
        }
        
        
        if(aux<s)
        {
            poz = i;
        }
        s = aux;
        aux = 0;
        
    }

    s = 0;
    
    for(j = 1; j<=m; j++)
    {
        a[poz][j]  = a[poz][j]*-1;
    }
    
    c = poz;
    
    
    poz = 1;
    
    for(i = 1; i<=n; i++)
    {
        s = s+a[i][1];
    }
    
    for(j = 2; j<=m; j++)
    {
        for(i = 1; i<=n; i++)
        {
            aux = aux+a[i][j];
        }
        if(aux<s)
        {
            poz = j;
        }
        s = aux;
        aux = 0;
        
    }
    
    if(a[c][poz]<0)
    {
        ok = false;
    }
    
    if(ok)
    {
        for(i = 1; i<=n; i++)
        {
        if(i!=c)
        {
         a[i][poz] = a[i][poz] * -1;   
        }
        }
    }else
    {
        for(i = 1; i<=n; i++)
        {
         a[i][poz] = a[i][poz] * -1;   
        
        }
    }
    

    
    for(i = 1; i<=n; i++)
    {
        for(j = 1; j<=m; j++)
        {
            aux = aux+a[i][j];
        }
    }
    
    fout<<aux;
    
    return 0;
}