#include <bits/stdc++.h>
using namespace std;

#define FOR(i,l,r) for(int i = (l);i < (r);i++)
#define ALL(x) (x).begin(),(x).end()
template<typename T> void chmax(T& a,const T& b){if(a < b) a = b;}
template<typename T> void chmin(T& a,const T& b){if(b < a) a = b;}
typedef long long ll;

int N;
vector<int> D;

int main()
{
	cin >> N;
	FOR(i,0,10){
		FOR(j,0,10){
			if(i) D.push_back(i);
			D.push_back(j);
		}
	}
	D.push_back(1);

	for(int i = D.size() - 1;i >= 0;i--){
		D [i] *= N;
	}
	for(int i = D.size() - 1;i > 0;i--){
		D [i - 1] += D [i] / 10;
		D [i] %= 10;
	}

	cout << D.front() << ".";
	FOR(i,1,D.size()){
		cout << D [i];
	}
	cout << endl;

	return 0;
}