#include <iostream>
#include <fstream>
using namespace std;

int main()
{ifstream fin("flip.int");
ofstream fout("flip.out");
int n, m, i, j, S=0, s1=0,s2=0, v[17][17];
cin>>n>>m;
for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
    cin>>v[i][j];
    i=0;
    while(i<=n){
for(j=1;j<=m;j++){
            s1=s1+v[i][j];
            s2=v[i][j]*(-1)+s2;}
            if(s1<s2){
                for(j=1;j<=m;j++){
                    v[i][j]=v[i][j]*(-1);
                }}
               i+=1;
               s1=0;s2=0;}
j=0;
while(j<=m){
    for(i=1;i<=n;i++){
        s1=s1+v[i][j];
        s2=v[i][j]*(-1)+s2;
        }
    if(s1<s2){
      for(i=1;i<=n;i++)
            v[i][j]=v[i][j]*(-1);}
j+=1;
s1=0;s2=0;}
    for(i=1;i<=n;i++){
     for(j=1;j<=m;j++)
      S=S+v[i][j];}
cout<<S;
fout<<S;
    return 0;
}