#include <fstream>
using namespace std;
int main()
{
	ifstream ii("flip.in");
	ofstream oo("flip.out");
	short n,m,i,j,k;
	ii >> n >> m;
	long a[n][m],s,ss;  short v[n];
	for (i=0;i<n;i++)
	{
		for (j=0;j<m;j++)
			ii >> a[i][j];
		v[i] = 0;
	}
	for (i=0;i<m;i++)
	{
		s = 0;
		for (j=0;j<n;j++)
			s += a[j][i];
		if (s < 0)
			for (j=0;j<n;j++)
				a[j][i] = -a[j][i];
	}
	ss = 0;  i = n;
	while (i >= 0)
	{
		i = n;
		while (v[i] && i >= 0)
		{
			v[i] = 0;  i--;
		}
		v[i] = 1;  ss = 0;
		for (j=0;j<n;j++)
		{
			if (v[j])
				for (k=0;k<m;k++)
					ss += a[j][k];
			else
				for (k=0;k<m;k++)
					ss -= a[j][k];
		}
		if (ss > s)
			s = ss;
	}
	oo << s;
	ii.close();  oo.close();
}