#include<fstream.h>
ifstream fin("flip.in");
ofstream fout("flip.out");
long int x[100][100];
int main()
{
	long int n,m,i,j,s1=0,s2=0;
	fin>>n;fin>>m;
	for (i=1;i<=n;i++)
	{
		for (j=1;j<=m;j++)
		{
			fin>>x[i][j];
			s1+=x[i][j];
			s2+=-x[i][j];
		}
		if (s2>s1)
		{
			for (j=1;j<=m;j++)
			{
				x[i][j]=-x[i][j];
			}
		}
		s1=0;s2=0;
	}
	for (j=1;j<=m;j++)
	{
		for (i=1;i<=n;i++)
		{
			s1+=x[i][j];
			s2+=-x[i][j];
		}
		if (s2>s1)
		{
			for (i=1;i<=n;i++)
			{
				x[i][j]=-x[i][j];
			}
		}
		s1=0;s2=0;
	}
	for (i=1;i<=n;i++)
	{
		for (j=1;j<=m;j++)
		{
			s1+=x[i][j];
		}
	}
	fout<<s1;
	return 0;
}