#include<iostream>
#include<fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int n,m,a[16][16],i,j,s1,s2,s;
void verificare(int i,int j)
{
    s1=s1+a[i][j];
    s2=s2+a[i][j]*-1;
    if(j!=m)
    verificare(i,j+1);
    else
    {
        if(s1<s2)
        for(j=1;j<=m;j++)
            a[i][j]=a[i][j]*-1;
        j=1;
        if(i!=n)
        {
            s1=s2=0;
            verificare (i+1,j);
        }
    }
}
void verificare2(int i,int j)
{
    s1=s1+a[i][j];
    s2=s2+a[i][j]*-1;
    if(i!=n)
    {verificare2(i+1,j);
    }
    else
    {
        if(s1<s2)
        for(i=1;i<=n;i++)
            a[i][j]=a[i][j]*-1;
        i=1;
        if(j!=m)
        {
            s1=s2=0;
            verificare2(i,j+1);
        }
    }
}
void citire(int i,int j)
{
    f>>a[i][j];
    if(j!=m)
    citire(i,j+1);
    else
    {
        j=1;
        if(i!=n)
        citire (i+1,j);
    }
}
void total(int i, int j)
{
    s=s+a[i][j];
     if(j!=m)
    total(i,j+1);
    else
    {
        j=1;
        if(i!=n)
        total (i+1,j);
    }
}
int main()
{
f>>n>>m;
i=j=1;s=0;s1=s2=0;
citire(i,j);
verificare(i,j);
s1=s2=0;
verificare2(i,j);
i=j=1;
total(i,j);
g<<s;

return 0;}