#pragma warning(disable : 4996)
#include <iostream>
#include <fstream>
#include <cmath>
#include <string.h>
using namespace std;

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


int main()
{
    int a[20][20], n, m, s, s1;
    f >> n >> m;
    for(int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
        {
            f >> a[i][j];
        }
    for (int i = 1; i <= n; i++)
    {
        s = 0;
        s1 = 0;
        for (int j = 1; j <= m; j++)
        {
            s += a[i][j];
            s1 += a[i][j] * -1;
        }
        if(s < s1) for (int j = 1; j <= m; j++)
        {
            a[i][j] *= -1;
        }
    }
    for (int i = 1; i <= m; i++)
    {
        s = 0;
        s1 = 0;
        for (int j = 1; j <= n; j++)
        {
            s += a[j][i];
            s1 += a[j][i] * -1;
        }
        if (s < s1) for (int j = 1; j <= n; j++)
        {
            a[j][i] *= -1;
        }
    }
    s = 0;
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
        {
            s += a[i][j];
        }

    g << s;
    return 0;
}