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

ifstream fin("flip.in");
ofstream fout("flip.out");
int main()
{   int v[20][20],N,M;
    fin>>N>>M;
    for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
            fin>>v[i][j];
        }
    }
    for(int i=1;i<=N;i++){
        int aux=0,sum2=0,sum=0;
            for(int j=1;j<=M;j++){
                sum+=v[i][j];
                aux=v[i][j]*-1;
                sum2+=aux;
            }
        if(sum2>sum){
            for(int j=1;j<=M;j++){
                v[i][j]=v[i][j] * -1;
            }
        }
    }
    for(int j=1;j<=M;j++){
        int aux=0,sum2=0,sum=0;
            for(int i=1;i<=N;i++){
                sum+=v[i][j];
                aux=v[i][j]*-1;
                sum2+=aux;
        }
        if(sum2>sum){
            for(int i=1;i<=N;i++){
                v[i][j]=v[i][j]*-1;
            }
        }
    }
    int s=0;
    for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
            s+=v[i][j];
        }
    }
    fout<<s;
    return 0;
}