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 <stdio.h>
#include <cstring>
#include <cstdlib>
#include <string>
#include <algorithm>
#include <vector>
#include <math.h>
#include <map>
#include <iomanip>
#include <limits>
#define rep(i, n) for(int i = 0; i < n; i++)
typedef long long ll;
using namespace std;

int asc(const void* a, const void* b) {
	return *(int*)a- *(int*)b;
}

int main()
{
	int n, cnt = 0;
	cin >> n;
	for(int i = 1; i <= n; i++) {
		if (i % 2 == 1) cnt++;
	}
	cout << (double)cnt / n << endl;
}