#include<fstream>
#include<stdlib.h>
using namespace std;
long lin[20],col[20],v[20][20],n,m,s,smax,k,i,j,sp,sn;
int main()
{
    ifstream f("flip.in");
    ofstream g("flip.out");
f>>n>>m;
for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
        {f>>v[i][j];
        s+=v[i][j];}
smax=s;
while(col[m+1]==0){
    k=1; s=0;
    col[k]++;
    while(col[k]>1)
    {
        col[k]=0;
        k++;
        col[k]++;
    }
    for(i=1;i<=n;i++)
        {sp=0;
        sn=0;
        for(j=1;j<=m;j++)
            {
                if(col[j]==1)
                {
                    if(v[i][j]>0)
                        sn+=v[i][j];
                    else
                        sp+=v[i][j]*(-1);
                }
                else{
                    if(v[i][j]>0)
                        sp+=v[i][j];
                    else
                        sn+=v[i][j]*(-1);
                }
            }
        s+=abs(sp-sn);
        if(s>smax)
            smax=s;
        }
}

g<<smax;
return 0;
}