//#include <bits/stdc++.h>
#include <fstream>

using namespace std;

ifstream cin("flip.in");
ofstream cout("flip.out");

int main()
{
    long long n, i, j, k, m, s1 = 0, s2 = 0, x[17][17], s = 0, mar = 0;
    cin >>n >> m;
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
        {
        cin >> x[i][j];
        s += x[i][j];
        }
        mar = s;
        s = 0;
    for (i = 1; i <= n; i++)
    {
        s1 = 0;
        s2 = 0;
        for (j = 1; j <= m; j++)
        {
            s1 += x[i][j];
            s2 += (x[i][j] * -1);
        }
        if (s2 > s1)
            for (j = 1; j <= m; j++)
            x[i][j] *= -1;
    }
    for (j = 1; j <= m; j++)
    {
        s1 = 0;
        s2 = 0;
        for (i = 1; i <= n; i++)
        {
            s1 += x[i][j];
            s2 += (x[i][j] * -1);
        }
        if (s2 > s1)
            for (i = 1; i <= n; i++)
            x[i][j] *= -1;
    }
    s = 0;
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
        s += x[i][j];
        cout << s;
}