#include <fstream.h>
int main()
{int n, m, x=1,i ,j;
long flip[16][16], sum=0, sum1=0;
ifstream f("flip.in");
f>>n>>m;
for(i=0;i<n;i++)
 for(j=0;j<m;j++)
  {f>>flip[i][j]; sum=sum+flip[i][j];}
sum1=sum;
f.close();
ofstream g("flip.out");
while(x)
 {x=0;
  for(i=0;i<n;i++)
   {for(j=0;j<m;j++)
     sum1=sum1-2*flip[i][j];
    if(sum1>sum) {sum=sum1; x=1; for(j=0;j<m;j++) flip[i][j]=(-1)*flip[i][j];}
    else sum1=sum;}
  for(j=0;j<n;j++)
   {for(i=0;i<m;i++)
     sum1=sum1-2*flip[i][j];
    if(sum1>sum) {sum=sum1; x=1; for(i=0;i<m;i++) flip[i][j]=(-1)*flip[i][j];}
    else sum1=sum;}}
g<<sum;
return 0;
}