#include<iostream.h>
#include<fstream.h>
int main(void)
{int ok,i,j;
 long int n,m,x[100][16],s1,s2;
 fstream f("flip.in",ios::in);
 fstream g("flip.out",ios::out);
 f>>n>>m;
 for(i=0;i<n;i++)for(j=0;j<m;j++)f>>x[i][j];
 ok=1;
 while(ok){ok=0;
	   for(i=0;i<n;i++){s1=s2=0;
			    for(j=0;j<m;j++){s1+=x[i][j];
					     s2+=(-1)*x[i][j];}
			    if(s2>s1){for(j=0;j<m;j++)x[i][j]=(-1)*x[i][j];
				      ok=1;}}
	   for(j=0;j<m;j++){s1=s2=0;
			    for(i=0;i<n;i++){s1+=x[i][j];
					     s2+=(-1)*x[i][j];}
			    if(s2>s1){for(i=0;i<n;i++)x[i][j]=(-1)*x[i][j];
				      ok=1;}}}
 s1=0;
 for(i=0;i<n;i++)for(j=0;j<m;j++)s1+=x[i][j];
 g<<s1;
 f.close();
 g.close();
 return 0;
}