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 mod 1000000007
#define MAX 100005
using namespace std; 

int findb(int b[],int i,int r){

	int ret=upper_bound(b,b+r,i)-b;
	if(ret==r)return -1;
	else return b[ret];

}  

int c2(int k){
	return(k*(k-1)/2);
}

int main(){

	int n;cin>>n;
	double p=n;
	if(n%2==0)p=1.0;
	else {p=(n+1);p=p/n;}
	p=p/2.0;
	cout<<p;
}