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 <iostream>
#include <fstream>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <list>
#define rep(i, n) for(int i=0; i<(n); ++i)
#define rep2(i, s, n) for(int i=s; i<(n); ++i)
#define sz(x) int(x.size())

typedef long long ll;

using namespace std;

/*******-c++14 don't include-*******/
template<typename T>
T gcd(T a, T b){if( b == 0)return a; return gcd(b, a%b); }
template<typename T>
T lcm(T a, T b){return a*b/gcd(a,b); }
/*******---------------------*******/

static const int INTINF = (2147483647);
static const ll LLINF = (1ll<<32);
static const int MAX = 100001;

int main(int argc, const char * argv[]) {
    // input from txt
    
    /////////
    //write//
    /////////
    
    int n;
    cin >> n;
    
    double res = n/2;
    if(n%2==1)res++;
    
    res/=n;
    
    printf("%.9f\n", res);
    
    return 0;
}