#include <fstream.h>
ifstream f("flip.in");
ofstream g("flip.out");
int s1,s2,smax,n,m,i,j,a[17][17];
int main ()
{
	f>>n>>m;
	for(i=1;i<=n;i++)
		{
			for(j=1;j<=m;j++)
			{
				f>>a[i][j];
				s1=s1+a[i][j];
				s2=s2+a[i][j]*(-1);
			}
			
			if(s1>s2) smax=smax+s1;
			else if(s2>s1) smax=smax+s2;
			else if (s2==s1) smax=smax+s1;
	}
	g<<smax;

}