#include<iostream>
#include<fstream>
short N,M;
 long a[100][100],S=0;
using namespace std;

int suma(){
    S=0;
    for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
            S+=a[i][j];
            }
        }
    }
int comutator(int x,int i){
    if(x==1){
        for(int j=1;j<=M;j++){
            a[i][j]*=-1;
            }
        }else{
            for(int j=1;j<=N;j++){
                    a[j][i]*=-1;
                    }
            }
    }

 int main()
 {int Smax;
    freopen("flip.in","r",stdin);
    cin>>N;
    cin>>M;
    for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
            cin>>a[i][j];
            }
        }
    fclose(stdin);
    suma();
    Smax=S;

for(int i=1;i<=N;i++){
        for(int j=1;j<=M;j++){
            comutator(1,i);
            suma();
            if(Smax<S)
                Smax=S;
            else
                comutator(1,i);

            comutator(2,j);
            suma();
            if(Smax<S)
                Smax=S;
            else
                comutator(2,j);
            }
        }
 freopen("flip.out","w",stdout);
cout<<Smax;
fclose(stdout);
 }