#include<fstream.h>
int a[17],b[17],n,m;
long x[16][16],smax=-9999999;

ifstream f("flip.in");
ofstream g("flip.out");

void citire(){  int i,j;
f>>n>>m;
for(i=0;i<n;i++)
   for(j=0;j<m;j++)
     f>>x[i][j];
for(i=0;i<=n;i++)
 a[i]=-1;
for(i=0;i<=m;i++)
b[i]=-1;
}
void zero(){
for(int i=0;i<=m;i++)
   b[i]=-1;
   }
int sum(){ int s=0,i,j,k;
for(i=0;i<n;i++)
   for(j=0;j<m;j++)
      s+=x[i][j]*a[i]*b[j];
return s;}

void algoritm(){
long s;
int i,j;
while(a[n]==-1)
{   i=0;  
    while(a[i]==1) a[i++]=-1;
       a[i]=1;
    zero();
    while(b[m]==-1)
       { i=0;
       
       while(b[i]==1) b[i++]=-1;
	  b[i]=1;
             
    s=sum();
      if(s>smax)
      smax=s;
}}} 


int main(){
citire();
algoritm();
g<<smax;
return 0;}