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)

//#define NDEBUG

#include <bits/stdc++.h>

#define StarBurstStream ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define iter(a) a.begin(), a.end()
#define riter(a) a.rbegin(), a.rend()
#define lsort(a) sort(iter(a))
#define gsort(a) sort(riter(a))
#define mp(a, b) make_pair(a, b)
#define pb(a) push_back(a)
#define pf(a) push_front(a)
#define pob pop_back()
#define pof pop_front()
#define F first
#define S second
#define printv(a, b) {bool pvaspace=false; \
for(auto pva : a){ \
    if(pvaspace) b << " "; pvaspace=true;\
    b << pva;\
}\
b << "\n";}
#define pii pair<int, int>
#define pdd pair<double, double>
#define pll pair<ll, ll>
#define modadd(a, b) (((a % MOD) + (b % MOD)) % MOD)
#define modtimes(a, b) (((a % MOD) * (b % MOD)) % MOD)

//#define TEST

typedef long long ll;
typedef unsigned long long ull;

using namespace std;

const ll MOD = 1000000007;
const ll MAX = 1LL << 60;


int main(){
    StarBurstStream

    int n;
    cin >> n;
    cerr << (n - (int)(n / 2)) << " " << n << "\n";
    cout << fixed << setprecision(10) << (n - (int)(n / 2)) / (double)n << "\n";

    return 0;
}