#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 sum()
{i=1;s=0;
    while(i!=n)


    {s1=0;s2=0;
        for(j=1;j<=m;j++)
        {s1=s1+a[i][j];
        s2=s2+a[i][j]*-1;}
        if(s1<s2)
            for(j=1;j<=m;j++)
            a[i][j]=a[i][j]*-1;
         i++;}
        j=1;
        while(j!=m)
    {s1=0;s2=0;
    for(i=1;i<=n;i++)
        {s1=s1+a[i][j];
        s2=s2+a[i][j]*-1;}
        if(s1<s2)
            for(i=1;i<=n;i++)
            a[i][j]=a[i][j]*-1;
                j++;}
                      for(i=1;i<=n;i++)
    {for(j=1;j<=m;j++)
    s=s+a[i][j];}
}
int main()
{
f>>n>>m;
for(i=1;i<=n;i++)
    {for(j=1;j<=m;j++)
    f>>a[i][j];}
sum();
g<<s;







return 0;}