#include <fstream>
#include <iostream>
using namespace std;
ifstream f("cifra.in");
ofstream g("cifra.out");

int ultim(int x)
{
	int y=x,x1=x;
	for (int i=1;i<=x;i++)
		y=(y*x1)%10;
	return y;
}
int main()
{
	int i,n,j,x=0,s=0;
	f>>n;
	for (i=1;i<=n;i++)
	{
		if (i%10==0)
			x=0;
		else
			if (i%10==1)
				x=1;
			else
				if (i%10==2)
				{
					if (i%4==0)
						x=6;
					else
						if (i%4==1)
							x=2;
						else
							if (i%4==2)
								x=4;
							else
								x=8;
				}
				else
					if (i%10==3)
					{
						if (i%4==0)
							x=1;
						else
							if (i%4==1)
								x=3;
							else
								if (i%4==2)
									x=9;
								else
									x=7;
					}
					else
						if (i%10==4)
						{
							if (i%2==0)
								x=6;
							else
								x=4;
						}
						else
							if (i%10==5)
								x=5;
							else
								if (i%10==6)
									x=6;
								else
									if (i%10==7)
									{
										if (i%4==0)
											x=1;
										else
											if (i%4==1)
												x=7;
											else
												if (i%4==2)
													x=9;
												else
													x=3;
									}
									else
										if (i%10==8)
										{
											if (i%4==0)
												x=6;
											else
												if (i%4==1)
													x=8;
												else
													if (i%4==2)
														x=4;
													else
														x=2;
										}
										else
											if (i%2==0)
												x=1;
											else
												x=9;
		s+=x;
		s=s%10;
	}
	cout<<s;
}