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