#include<fstream.h>
int c[17],l[17],i,j,k,k2,m,n,s,si,negativ,a[17][17];
int main()
{
ifstream in("flip.in");
ofstream out("flip.out");
in>>m;
in>>n;
for(i=1;i<=m;i=i+1)
for(j=1;j<=n;j=j+1)
{in>>a[i][j];
 l[i]=l[i]+a[i][j];
 c[j]=c[j]+a[i][j];
 si=si+a[i][j];
}
negativ=1;
do
{
for(i=1;i<=m;i=i+1)
if(l[i]<0)
	   {l[i]=0;
	   for(j=1;j<=n;j=j+1)
	   { a[i][j]=-a[i][j];
	   l[i]=l[i]+a[i][j];
	   c[j]=c[j]+2*a[i][j];
	   }
	   }
for(j=1;j<=n;j=j+1)
if(c[j]<0)
	   {negativ=0;
	    c[j]=0;
	   for(i=1;i<=m;i=i+1)
	   { a[i][j]=-a[i][j];
	   c[j]=c[j]+a[i][j];
	   l[i]=l[i]+2*a[i][j];
	   if(l[i]<0) negativ=1;
	   }
	   }
   else negativ=0;
}while(negativ==1);
s=0;
for(i=1;i<=m;i=i+1)
s=s+l[i];
if(si>s) out<<si;
       else  out<<s;
in.close();
out.close();
return 0;
}