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 <stdio.h>
#include <iostream>
#include <string.h>
#include <limits.h>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <set>

typedef unsigned long long ULLONG;
typedef long long LLONG;

template <class _T> static _T tp_abs(const _T& a) {
	return ((a < 0) ? (a * -1) : a);
}
template <class _T> static _T tp_min(_T a, _T b) {
	return a < b ? a : b;
}
template <class _T> static _T tp_max(_T a, _T b) {
	return a > b ? a : b;
}
template<class _T> static void get1int(_T& a) {
	const char* fmt = " %d";
	if (sizeof(_T) == sizeof(long long)) {
		fmt = " %lld";
	}

	if (scanf(fmt, &a) < 0) {
		printf("g1int Error\n");
	}
}
template<class _T> static void get2int(_T& a, _T& b) {
	const char* fmt = " %d %d";
	if (sizeof(_T) == sizeof(long long)) {
		fmt = " %lld %lld";
	}

	if (scanf(fmt, &a, &b) < 0) {
		printf("g2int Error\n");
	}
}
template<class _T> static void get3int(_T& a, _T& b, _T& c) {
	const char* fmt = " %d %d %d";
	if (sizeof(_T) == sizeof(long long)) {
		fmt = " %lld %lld %lld";
	}

	if (scanf(fmt, &a, &b, &c) < 0) {
		printf("g3int Error\n");
	}
}
static void getstring(char* buff) {
	if (scanf(" %s", buff) < 0) {
		printf("getstr error!\n");
	}
}
static const long long MOD_NUM = 1000000007LL;

static void A_task();

int main()
{
	A_task();
	fflush(stdout);
	return 0;
}

static void A_task()
{
	int N;
	get1int(N);

	int odd = N / 2;
	if (N % 2) odd++;

	printf("%.7lf\n", (double)odd / (double)N);
}