#include <bits/stdc++.h>
using namespace std;
ifstream fin ("flip.in");
ofstream fout ("flip.out");
void read();
int n, m, a[20][20];
int suma()
{
    int s = 0;
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
            s+=a[i][j];
    return s;
}
int bkt(int k)
{
    int s = 0;
    if(k == n+m+1)
        return suma();
    ///flip
    if(k > n)
    {
        s = max(s, bkt(k+1));
        for(int i=1; i<=n; i++)
            a[i][k-n]=-a[i][k-n];
        s = max(s, bkt(k+1));
    }
    else
    {
        s = max(s, bkt(k+1));
        for(int j=1; j<=m; j++)
            a[k][j]=-a[k][j];
        s = max(s, bkt(k+1));
    }
    return s;
}
int main()
{
    read();
    fout << bkt(1);
    return 0;
}
void read()
{
    fin >> n >> m;
    for(int i=1; i<=n; i++)
        for(int j=1; j<=m; j++)
            fin >> a[i][j];
}