# include <fstream.h>
# include <math.h>
using namespace std;
ifstream f("cifra.in");
ofstream g("cifra.out");
int main ()
{
	float n, u;
	int i, o, s;
	f>>n;
	s=0;
	for(i=1;i<=n;i++)
	{	u=i;
		s=s+pow(u,u);
	}
	o=s%10;
	g<<o;
	return 0;
}