#include <iostream>
#include <fstream>
using namespace std;
int n,m,i,j,v[20][20],s;
int main()
{
    ifstream f ("flip.in");
    ofstream g ("flip.out");
    f>>n>>m;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            f>>v[i][j];
    for (i=1;i<=n;i++)
    {
        s=0;
        for (j=1;j<=m;j++)
            s=s+v[i][j];
        if (s<0) for (j=1;j<=m;j++)
                    v[i][j]=v[i][j]*(-1);
    }
     for (j=1;j<=m;j++)
    {
        s=0;
        for (i=1;i<=n;i++)
            s=s+v[i][j];
        if (s<0) for (i=1;i<=n;i++)
                    v[i][j]=v[i][j]*(-1);
    }
    s=0;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            s=s+v[i][j];
   g<<s;
}