#include <fstream>
using namespace std;

int power(long long,long long);

int main()
{
	int n,s;
	fstream f,g;
	f.open("cifra.in",fstream::in);
	g.open("cifra.out",fstream::out);
	f>>n;
	s=0;
	for (int i=1;i<=n;i++)
		s=(s+power(i,i))%10;
	g<<s;
	g.close();
	return 0;
}

int power(long long a,long long p)
{
	int sol=1;
	for (int i=0;(1<<i)<=p;i++)
	{
		if ( ((1<<i)&p) >0)
			sol=(sol*a)%10;
		a=(a*a)%10;
	}
	return sol;
}