#include <fstream>

using namespace std;

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

int main()
{
    int N,M,i,j,s1,s2,s;
    int a[17][17];
    cin>>N>>M;
    for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)
            cin>>a[i][j];
    for (i=1;i<=N;i++)
    {
        s1=0;
        s2=0;
        for (j=1;j<=M;j++)
        {
            s1=s1+a[i][j];
            s2=s2+-1*a[i][j];
        }
        if (s2>s1)
            for (j=1;j<=M;j++)
                a[i][j]=a[i][j]*-1;
    }
    for (j=1;j<=M;j++)
    {
        s1=0;
        s2=0;
        for (i=1;i<=N;i++)
        {
            s1=s1+a[i][j];
            s2=s2+-1*a[i][j];
        }
        if (s2>s1)
            for (i=1;i<=N;i++)
                a[i][j]=a[i][j]*-1;
    }
    s=0;
    for (i=1;i<=N;i++)
        for (j=1;j<=M;j++)
            s=a[i][j]+s;
    cout<<s;
    return 0;
}