#include<stdio.h>
int a[20][20];
int main()
{
	freopen("flip.in","r",stdin);
	freopen("flip.out","w",stdout);
	long m,n,i,j,s1,s2;
	scanf("%ld",&n);
	scanf("%ld",&m);
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			scanf("%d",&a[i][j]);
		for(i=1;i<=n;i++)
		{
			s1=0;
			s2=0;
			for(j=1;j<=m;j++)
			{
				s1=s1+a[i][j];
				s2=s2+a[i][j]*-1;
			}
			if(s2>s1)
				for(j=1;j<=m;j++)
					a[i][j]=a[i][j]*-1;
		}
		for(j=1;j<=m;j++)
		{
			s1=0;
			s2=0;
			for(i=1;i<=n;i++)
			{
				s1=s1+a[i][j];
				s2=s2+a[i][j]*-1;
			}
			if(s2>s1)
				for(i=1;i<=n;i++)
					a[i][j]=a[i][j]*-1;
		}
		s1=0;
		for(i=1;i<=n;i++)
			for(j=1;j<=m;j++)
				s1=s1+a[i][j];
			printf("%ld",s1);
			return 0;
}