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: Accepted)

#include <stdio.h>

#ifdef DEBUG
#define DPRTF(x) printf x
#define TRACE (printf("%s:%s:%d\n", __FILE__, __func__, __LINE__))
#define ERR(x) (TRACE, (x))
#else
#define DPRTF(x)
#define TRACE
#define ERR(x) (x)
#endif

int main(int argc, char *argv[])
{
    int N = 0;
    scanf("%d", &N);

    if (N % 2 == 0) {
        printf("0.5000000000\n");
    } else if (N % 2 == 1) {
        printf("%f\n", (float)((float)((int)(N/2)+1)/(float)N));
    }

    return 0;
}