#include<bits/stdc++.h>
#define VMAX 17
#define close return 0; fin.close; fout.close
using namespace std;
ifstream fin("flip.in");
ofstream fout("flip.out");
vector<int> col(17);
vector<int> lin(17);
int main()
{
    int n, m, v[VMAX][VMAX];
    fin >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            fin >> v[i][j];
        }
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            col[j] += v[i][j];
            lin[i] += v[i][j];
        }
    }
    int s = 0;
    for (int i = 1; i <= n; i++)
    {
        if (lin[i] < 0)
        {
            for (int j = 1; j <= m; j++)
            {
                v[i][j] *= -1;
            }
        }
    }
    for (int i = 1; i <= m; i++)
    {
        if (col[i] < 0)
        {
            for (int j = 1; j <= n; j++)
            {
                v[j][i] *= -1;
            }
        }
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
            s += v[i][j];
    }
    fout << s;
}