#include <fstream>

using namespace std;

ifstream in("flip.in");
ofstream out("flip.out");

int a[17][17],x[34],v[34],maxim;
unsigned int N,M;

int main()
{
	in>>N>>M;
	for(unsigned int i=1;i<=N;i++)
		for(unsigned int j=1;j<=M;j++)in>>a[i][j];
	unsigned int gata=0;
	while(gata==0)
	{
		unsigned int i=N+M;
		while(i>0 && v[i]==1)
		{
			v[i]=0; i--;
		}
		if(i==0)gata=1;
		else 
		{
			v[i]=1;
			
			for(unsigned int j=1;j<=N+M;j++)
				if(v[j]==1)
					if(j<=N)
						for(unsigned int b=1;b<=M;b++)a[j][b]=a[j][b]*(-1);
					else
						for(unsigned int b=1;b<=N;b++)a[b][j]=a[b][j]*(-1);
			int sum=0;
			for(unsigned int b=1;b<=N;b++)
				for(unsigned int j=1;j<=M;j++)sum=sum+a[b][j];
			if(maxim<sum)maxim=sum;
		}
	}
	out<<maxim;
	return 0;
}