#include <bits/stdc++.h>
using namespace std;
ifstream in("flip.in");
ofstream out("flip.out");
int a[17][17],s,s1;
short n,m,i,j;
int main()
{
    in>>n>>m;
    for(i=1; i<=n; ++i)
        for(j=1; j<=m; ++j)
            in>>a[i][j];
    for(j=1; j<=m; ++j)
    {
        for(i=1,s=0,s1=0; i<=n; ++i)
            s+=a[i][j],s1+=a[i][j]*(-1);
        if(s1>s)
            for(i=1; i<=n; ++i)
                a[i][j]*=-1;
    }
    for(i=1; i<=n; ++i)
    {
        for(j=1,s=0,s1=0; j<=m; ++j)
            s+=a[i][j],s1+=a[i][j]*(-1);
        if(s1>s)
            for(j=1; j<=m; ++j)
                a[i][j]*=-1;
    }
    for(i=1,s=0; i<=n; ++i)
        for(j=1; j<=m; ++j)
            s+=a[i][j];
    out<<s;
}