#include<stdio.h>
int n,m,a[32][32],i,j,b[64],u,c[32][32];
long long s,s1;
int main()
{
	freopen("flip.in","r",stdin);
	freopen("flip.out","w",stdout);
	scanf("%d %d",&n,&m);
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			scanf("%d",&c[i][j]);
		
	while(b[n+m+1]==0)
	     {
			for(i=1;i<=n;i++)
				for(j=1;j<=m;j++)
					a[i][j]=c[i][j];
			 i=1;
			while(b[i]!=0)
				i++;
			for(j=1;j<i;j++)
				b[j]=0;
			b[i]=1;
			for(i=1;i<=n;i++)
			   
				   if(b[i]==1)
					 {
						 for(j=1;j<=m;j++)
						    a[i][j]*=-1;
				      }
			for(i=n+1;i<=n+m;i++)
			   {
				   if(b[i]!=0)
				      {
						  u=i-n;
						  for(j=1;j<=n;j++)
						     a[j][u]*=-1;
					   }
				}
	        s1=0;
			for(i=1;i<=n;i++)
				for(j=1;j<=m;j++)
					s1+=a[i][j];
				if(s1>s)
					s=s1;
		
	}
		
		printf("%d",s);
		
		return 0;}