#include <iostream>
#include <fstream>
using namespace std;

int main()
{ifstream f("flip.in");
    ofstream g("flip.out");
    int m,n,i,j,s=0,k,sl1=0,sl2=0,sc1=0,sc2=0,sf=0;
    long long a[17][17],b[17][17];
    f>>n>>m;
    for (i=1;i<=n;i++)
    for (j=1;j<=m;j++)
        {f>>a[i][j];b[i][j]=a[i][j];sf=sf+a[i][j];}
    for(j=1;j<=m;j++)
        {
            s=0;
            for (i=1;i<=n;i++)
                s=s+a[i][j];
             if (s<0)
              for (k=1;k<=n;k++)
                a[k][j]=a[k][j]*-1;
        }

for (i=1;i<=n;i++)
        {
            s=0;

        for (j=1;j<=m;j++)
            {
            s+=a[i][j];

            }
            if (s<0)
              for (k=1;k<=m;k++)
              a[i][k]=a[i][k] *-1;
        }
  s=0;
  for (i=1;i<=n;i++)
    for (j=1;j<=m;j++)
        s=s+a[i][j];
    if (s>sf)
        sf=s;

            for(j=1;j<=m;j++)
        {
            s=0;
            for (i=1;i<=n;i++)
                s=s+b[i][j];
             if (s<0)
              for (k=1;k<=n;k++)
                b[k][j]=b[k][j]*-1;
        }

for (i=1;i<=n;i++)
        {
            s=0;

        for (j=1;j<=m;j++)
            {
            s+=b[i][j];

            }
            if (s<0)
              for (k=1;k<=m;k++)
              a[i][k]=b[i][k] *-1;
        }

              s=0;
  for (i=1;i<=n;i++)
    for (j=1;j<=m;j++)
        s=s+b[i][j];
    if (s>sf)
        sf=s;


                g<<sf;cout<<sf;
    return 0;
}