#include <iostream>
#include <fstream>

using namespace std;

int n, m, i, j, v[18][18], b[18][18], x[35], k;
long long c, rez;

long long suma ()
{
    for (int i = 1; i <= k; i++)
    {
        for (int j = 1; j <= m; j++)
            b[x[i]][j] *= -1;
    }
    
    long long sum = 0;
    long long c = 0;
    for (j = 1; j <= m; j++)
    {
        c = 0;
        for (i = 1; i <= n; i++)
        {   c += b[i][j];   b[i][j] = v[i][j];   }
        
        if (c > 0)  sum += c;
        else sum -= c;
    }
    
    return sum;
}

void back (int p)
{
    long long c;
    for (int i = x[p-1] + 1; i <= n; i++)
    {
        x[p] = i;
        if (p == k)
        {
            c = suma();
            if (c > rez)    rez = c;
        }
        else    back(p + 1);
    }
}

int main () {
    
    ifstream fin("flip.in");
    ofstream fout("flip.out");
    
    fin >> n >> m;
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
        {
            fin >> v[i][j];
            b[i][j] = v[i][j];
            rez += v[i][j];
        }
    
    for (k = 1; k <= n; k++)
        back(1);
    
    fout << rez << "\n";
    return 0;
}