# include <fstream>

using namespace std;
ifstream fin("flip.in");
ofstream fout("flip.out");

int n,v[1005],ok,m,a[1005][1005],b[1005][1005],maxim,costCurent,suma;

int main(){
    fin>>n>>m;
    for (int i=1;i<=n;i++)
        for (int j=1;j<=m;j++)
            fin>>a[i][j];


    for(int i=1;i<=n;i++){
        v[i]=0;
    }

    while(v[0]==0){

        for (int i=1;i<=n;i++)
            for (int j=1;j<=m;j++)
                b[i][j] = a[i][j];



        int i=n;
        while(v[i]==1){
            v[i]=0;
            i--;
        }
        v[i]=1;
        ok=0;
        for(int i=1;i<=n;i++)
            if(v[i]==1){
                for (int j=1;j<=m;j++)
                    b[i][j] = -b[i][j];
            }
        costCurent = 0;
        for (int j=1;j<=m;j++) {
            suma = 0;
            for (int i=1;i<=n;i++)
                suma += b[i][j];
            if (suma > 0)
                costCurent += suma;
            else
                costCurent -= suma;
        }
        if (costCurent > maxim)
            maxim = costCurent;

    }
    fout<<maxim;
}