/* -*- coding: utf-8 -*-
 *
 * 428.cc: No.428 小数から逃げる夢 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const string D =
  "0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";

/* typedef */

typedef vector<int> vi;

/* global variables */

/* subroutines */

/* main */

int main() {
  vi d;
  for (int i = D.size() - 1; i >= 0 && D[i] >= '0' && D[i] <= '9'; i--)
    d.push_back(D[i] - '0');
  int fp = d.size();
  //printf("fp=%d\n", fp);

  int n;
  cin >> n;

  int co = 0;
  vi e;
  for (int i = 0; i < d.size(); i++) {
    int di = d[i] * n + co;
    co = di / 10;
    e.push_back(di % 10);
  }
  while (co > 0) {
    e.push_back(co % 10);
    co /= 10;
  }
  //printf("%lu\n", e.size());

  if (fp >= e.size()) putchar('0');
  else
    for (int i = e.size() - 1; i >= fp; i--) putchar(e[i] + '0');
  putchar('.');
  for (int i = fp - 1; i >= 0; i--) putchar(e[i] + '0');
  putchar('\n');
  
  return 0;
}