#define _USE_MATH_DEFINES
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include<iomanip>

//#include<bits/stdc++.h>



using namespace std;




int main() {
	
	string s="1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
	int r[199]={};
	int y;
	cin>>y;
	int t=0;
	for(int i=189;i>=0;i--){
		t+=(s[i]-'0')*y;
		r[i]=t%10;
		t/=10;
	}
	cout<<t<<'.';
	for(int i=0;i<190;i++)
		cout<<r[i];
	cout<<endl;

	return 0;
}