#include <fstream>

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

int main()
{
    int n, m, i, j, c=1, v[18][18], S1, S2;
    f>>n>>m;
    for (i=0;i<n;i++)
        for (j=0;j<m;j++)
            f>>v[i][j];
    while (c!=0)
    {
        c=0;
        for (i=0;i<n;i++)
        {
            S1=0;
            S2=0;
            for (j=0;j<m;j++)
            {
                S1=S1+v[i][j];
                S2=S2-v[i][j];
            }
            if (S1<S2)
                for (j=0;j<m;j++)
                {
                    v[i][j]=-v[i][j];
                    c++;
                }
        }
        for (j=0;j<m;j++)
        {
            S1=0;
            S2=0;
            for (i=0;i<n;i++)
            {
                S1=S1+v[i][j];
                S2=S2-v[i][j];
            }
            if (S1<S2)
                for (i=0;i<n;i++)
                {
                    v[i][j]=-v[i][j];
                    c++;
                }
        }
    }
    S1=0;
    for (i=0;i<n;i++)
        for (j=0;j<m;j++)
            S1=S1+v[i][j];
    g<<S1;
    return 0;
}