#include<fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int a[100][16],n,m,s,s1,s2,i,j,k;
int main()
{
    f>>n>>m;
    for (i=1;i<=n;++i)
        for( j=1;j<=m;++j)
            f>>a[i][j];
     for ( j=1;j<=m;++j)
    {
        for ( i=1;i<=n;++i)
        {
            s1+=a[i][j];
            s2+=a[i][j]*(-1);
        }
        if(s2>s1)
            for(k=1;k<=m;++k)
                a[i][k]=a[i][k]*(-1);
    }
    for ( i=1;i<=n;++i)
    {
        for ( j=1;j<=m;++j)
            {
            s1+=a[i][j];
            s2+=a[i][j]*(-1);
            }
        if(s2>s1)
            for( k=1;k<=m;++k)
                a[i][k]=a[i][k]*(-1);
    }
    for ( i=1;i<=n;++i)
        for (j=1;j<=m;++j)
            s+=a[i][j];
    g<<s;
    g.close();
    return 0;
}