#include<fstream.h>
long long int a[20][20],s,smax;
int n,m,x[20];

void coloane()
{
    int i,j;
    long long int sc;
    for (i=1;i<+n;i++)
        if (x[i]==1)
            for (j=1;j<=m;j++)
                a[i][j]=(-1)*a[i][j];
    for (j=1;j<=m;j++)
        {
            sc=0;
            for (i=1;i<=n;i++)
                sc+=a[i][j];
            if (sc<0)
                for (i=1;i<=n;i++)
                    a[i][j]=(-1)*a[i][j];
        }
}

int suma()
{
    long long int ss;
    ss=0;
    int i,j;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            ss+=a[i][j];
    return ss;
}

void back(int k)
{
    int i;
    for (i=0;i<=1;i++)
        {
            x[k]=i;
            if (k==n)
                {
                    coloane();
                    s=suma();
                    if (s>smax)
                        smax=s;
                }
            else
                back(k+1);
        }
}

int main()
{
    ifstream in("flip.in");
    in>>n>>m;
    int i,j;
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            in>>a[i][j];
    in.close();
    
    back(1);
    
    ofstream out("flip.out");
    out<<smax;
    out.close();        

    return 0;
}