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)

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>



int main()
{
	int A, B;
	scanf("%d %d", &A, &B);

	

	int x, min, Ans = 0;
	if (A >= B) min = B;
	else min = A;

	for (x = min; x > 0; x--) {

		int  t, m = 0;

		if (x >= 4) {
			for (t = 2; t < x; t++) {
				if (x % t == 0) {
					m++;
					break;
				}
				
			}
		}

		if (A % x == 0 && B % x == 0 && m==0) Ans++;
	}


	printf("%d", Ans);
	
}