#include <fstream.h>
ifstream fin("flip.in");
ofstream fout("flip.out");
int main()
{
	int a[6][4] ,i , j,n , m, s[100]={0},v = 0,p[100]={0};
	fin >> n >> m;
	s[1] = 0;
	for(i = 1;i <= n;i++)
		for(j = 1;j <= m;j++)
		{
			fin >> a[i][j];
			s[i] = s[i] + a[i][j];
		}
	for(i = 1;i <= n;i++)
		if(s[i] < 0)
			for(j = 1;j <= m;j++)
				a[i][j] = -1 * a[i][j] ;
	for(j = 1;j <= m;j++)
		for(i = 1;i <= n;i++)
			p[j] = a[i][j] + p[j];
	for(i = 1;i <= m;i++)
		if(p[i] < 0) p[i] = -1 * p[i];
	for(i = 1;i <= m;i++)
		v=v+p[i];
	fout << v;
	return 0;
}