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

int main() {
  string s = "142857";
  int n;
  cin >> n;
  cout << 0;
  if (n == 0) {
    cout << endl;
    return 0;
  }
  cout << ".";
  int cnt = 0;
  for (int i = 0; i < n; i++) {
    cout << s[cnt];
    cnt++;
    cnt %= 6;
  }
  cout << endl;
  return 0;
}