#include <iostream>
#include <fstream>

using namespace std;

ifstream f("flip.in");
ofstream g("flip.out");

void recalc(int a[][17], int n, int m)
{
    for(int i = 0; i < n; i ++)
        a[i][m] = 0;
    for(int i = 0; i < m; i ++)
        a[n][i] = 0;
    for(int i = 0; i < n; i ++)
        for(int j = 0; j < m; j ++)
        {
            a[i][m] += a[i][j];
            a[n][j] += a[i][j];
        }
}

int main()
{
    int n, m;
    int a[17][17] = {0};
    f >> n >> m;
    for(int i = 0; i < n; i ++)
        for(int j = 0; j < m; j ++)
        {
            f >> a[i][j];
            a[i][m] += a[i][j];
            a[n][j] += a[i][j];
        }
    bool k = 1;
    while(k)
    {
        k = 0;
        for(int i = 0; i < n; i ++)
        {
            if(a[i][m] < 0 )
            {
                for(int j = 0; j < m; j ++)
                    a[i][j] *= -1;
                k = 1;
            }
        }
        recalc(a, n,m);
        for(int i = 0; i < m; i ++)
        {
            if(a[n][i] < 0 )
            {
                for(int j = 0; j < n; j ++)
                    a[j][i] *= -1;
                k = 1;
            }
        }
        recalc(a, n,m);
    }
    int s = 0;
    for(int i = 0; i < n; i ++)
        s += a[i][m];

    g << s;
    return 0;
}