#include<fstream>
#include<math.h>
using namespace std;
int main()
{int n,i,z,y,S=0,P;
ifstream f("cifra.in");
ofstream g("cifra.out");
f>>n;
for(i=1;i<=n;i++)
{
	z=i;
	y=i;
	P=1;
	while(z!=0);
	{P=P*y;
	z=z-1;}
	S=S+P;
	S=S%10;}
g<<n<<endl;
f.close();
g.close();
return 0;
}