#include <fstream>

using namespace std;

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

unsigned int n,m,a[17][17],x[33],max1;

void rez(unsigned int k)
{
	unsigned int sum=0;
	for(unsigned int i=1;i<=k;i++)
		if(x[i]==1)
		{
			if(i<=n)for(unsigned int j=1;j<=n;j++)a[i][j]=a[i][j]*(-1);
			else for(unsigned int j=1;j<=m;j++)a[j][i]=a[j][i]*(-1);
		}
	for(unsigned int i=1;i<=n;i++)
		for(unsigned int j=1;j<=m;j++)
			sum=sum+a[i][j];
	if(sum>max1)max1=sum;
}

void back(unsigned int k)
{
	for(unsigned int i=x[k-1]+1;i<=n+m;i++)
	{
		x[k]=i;
		rez(k);
		if(k<n+m)back(k+1);
	}
}

void citire()
{
	in>>n>>m;
	for(unsigned int i=1;i<=n;i++)
		for(unsigned int j=1;j<=m;j++)
			in>>a[i][j];
}

int main()
{
	citire();
	back(1);
	out<<max1;
	in.close();
	out.close();
	return 0;
}