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

return 0;}