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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main(void){
	
	long A;
	long B;
	long C;

	scanf("%d", &A);
	scanf("%d", &B);

	if(A < B){
		C = A;
	}else{
		C = B;
	}

	int cnt = 1;
	for(int i = 2; i <= C; i++){
		if(A % i == 0 && B % i == 0){
			cnt++;
			for(int j = i * 2; j <= C; j * 2){
				if(A % j == 0 && B % j == 0){
					cnt--;
				}
			}
		}
	}

	printf("%d", cnt);

	return 0;
}