Problem:
Score : 100 points

Problem Statement

Given is an integer N.

Takahashi chooses an integer a from the positive integers not greater than N with equal probability.

Find the probability that a is odd.

Constraints

1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:

N

Output

Print the probability that a is odd.
Your output will be considered correct when its absolute or relative error from the judge's output is at most 10^{-6}.

Sample Input 1

4

Sample Output 1

0.5000000000

There are four positive integers not greater than 4: 1, 2, 3, and 4. Among them, we have two odd numbers: 1 and 3. Thus, the answer is \frac{2}{4} = 0.5.

Sample Input 2

5

Sample Output 2

0.6000000000

Sample Input 3

1

Sample Output 3

1.0000000000

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define INF INT_MAX
#define ll  long long
#define ull unsigned long long
#define rep(i,n) for(ll i=0; i<n; ++i)
#define FOR(i, s, e) for(ll i=s; i<e; ++i)
#define MOD 1000000007
using namespace std;
template<class T> inline bool chmin(T& a, T b) { if(a>b) {a=b; return true;} return false;}
template<class T> inline bool chmax(T& a, T b) { if(a<b) {a=b; return true;} return false;}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  float N; cin >> N;
  int odd = 0;
  for(int i=1; i<=N; ++i) {
    if(i%2) ++odd;
  }
  cout << odd/N << endl;
}