#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)
#define FOR(i,b,e) for (int i=(int)(b); i<(int)(e); i++)
#define ALL(x) (x).begin(), (x).end()

const double PI = acos(-1);

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  string s = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
  string n;
  cin >> n;

  vector<int> val(200);
  REP (i, n.length()) REP (j, s.length()) {
    val[i+j] += (n[n.length()-1-i] - '0') * (s[s.length()-1-j] - '0');
  }

  REP (i, 199) {
    val[i+1] += val[i] / 10;
    val[i] %= 10;
  }

  string ret;
  REP (i, 190)
    ret += char('0' + val[i]);
  ret += '.';
  FOR (i, 190, 200)
    ret += char('0' + val[i]);

  reverse(ALL(ret));
  int pos = 0;
  while (ret[pos] == '0') ++pos;
  ret = ret.substr(pos);

  if (ret[0] == '.')
    ret = "0" + ret;

  cout << ret << endl;
  
  return 0;
}