#include <fstream>
using namespace std;
ifstream f("flip.in");
ofstream g("flip.out");
int m, n, mat[17][17], i, j, l, sbm[17], sc[17], s_tmp, smax=0, sl;
int main()
{
    f>>n>>m;
    for (i=1; i<=n; i++)
        for (j=1; j<=m; j++)
        {
            f>>mat[i][j];
            sc[j]+=mat[i][j];
        }
    for(i=1; i<=m; i++)
        smax+=sc[i];
    while (sbm[m+1] == 0)
    {
        s_tmp=0;
        sl=0;
        l=1;
        while (sbm[l]==1)
        {
            sbm[l]=0;
            l++;
        }
        sbm[l]=1;
        if (sbm[m+1]==0)
        {
            for (i=1; i<=m; i++)
            {
                if (sbm[i]==1 && sc[i]<0)
                {
                    for (j=1; j<=n; j++)
                        sl+=mat[i][j];
                    if (sl<0)
                        s_tmp+=sl*-1;
                    else
                        s_tmp+=sl;
                }
                else if (sc >0)
                    s_tmp+=sc[i];
            }
            if (smax < s_tmp)
                smax = s_tmp;
        }
    }
    g<<smax;
    return 0;
}