#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;}   
  if(x==0)   
  for(j=0;j<m;j++)   
   {for(i=0;i<n;i++)   
     sum1=sum1-2*flip[i][j];   
    if(sum1>sum) {sum=sum1; x=1; for(i=0;i<n;i++) flip[i][j]=(-1)*flip[i][j];}   
    else sum1=sum;}}   
g<<sum;   
g.close();

return 0;   
}