#include<iostream>
#include<fstream>
#include<math.h>
#include<algorithm>

using namespace std;
ifstream fin("flip.in");
ofstream fout("flip.out");
int a[18][18],n,i,j,v[18],maxi,b[18][18],m,s,sum;

int main(){
    fin>>n>>m;
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
        {
            fin>>a[i][j];
            b[i][j]=a[i][j];
        }
    while(v[0]==0)
    {
        i=m;
        while(v[i]==1)
        {
            v[i]=0;
            i--;
        }
        v[i]=1;
        for(i=1;i<=n;i++)
            for(j=1;j<=m;j++)
                if(v[j]==1)
                    b[i][j]=-a[i][j];
                else
                    b[i][j]=a[i][j];
        sum=0;
        for(i=1;i<=n;i++)
        {
            s=0;
            for(j=1;j<=m;j++)
                s=s+b[i][j];
            if(s<0)
                sum-=s;
            else
                sum+=s;
        }
        if(maxi<sum)
            maxi=sum;
    }
    fout<<maxi;
    fin.close();
    fout.close();
    return 0;
}