#include <iostream>
#include <fstream>
using namespace std;
int a[17][17],m,n,rez=0,var[17][17],b[34];
ifstream g("flip.in");
ofstream f("flip.out");
void cop()
{int i,j;
for (i=1;i<=m;i++)
for (j=1;j<=n;j++)
var[i][j]=a[i][j];
}
void sum ()
{int i,j,s=0;
for (i=1;i<=(m+n);i++)
{if (i<=m)
{for (j=1;j<=n;j++) var[i][j]=b[i]*var[i][j];}
if (i>m)
{for (j=1;j<=m;j++) var[j][i-m]=b[i]*var[j][i-m];}}
for (i=1;i<=m;i++)
{for (j=1;j<=n;j++)
{f<<var[i][j]<<" ";
s=s+var[i][j];}}
if (s>rez) rez=s;
}
void citire()
{int i,j;
for (i=1;i<=m;i++)
{for (j=1;j<=n;j++)
g>>a[i][j];}}
void bkt(int k)
{if (k==(m+n)) {b[k]=1;
                cop();
                sum();
                b[k]=-1;
                cop();
                sum();
               }
if (k<(m+n)) {b[k]=1;
              bkt(k+1);
              b[k]=-1;
              bkt(k+1);}

}
int main()
{g>>m>>n;
citire();
bkt(1);
f<<rez;
f.close();
g.close();
return 0;
}