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)

/*2019/09/13 */
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>
#define MOD 1000000007
#define MIN 999999999
#define MAX -999999999
typedef long long int ll;
typedef unsigned long long int ull;
void llswap(ll *x,ll *y){ll tmp;tmp=*x;*x=*y;*y=tmp;}
void swap(int *x,int *y){int tmp;tmp=*x;*x=*y;*y=tmp;}
int rmax(int x,int y){return x>y?x:y;}
int rmin(int x,int y){return x>y?y:x;}
ll llrmax(ll x,ll y){return x>y?x:y;}
ll llrmin(ll x,ll y){return x>y?y:x;}
int asc(const void *a,const void *b){return *(int*)a-*(int*)b;}
int desc(const void *a,const void *b){return *(int*)b-*(int*)a;}
int llasc(const void *a,const void *b){return *(ll*)a-*(ll*)b;}
int lldesc(const void *a,const void *b){return *(ll*)b-*(ll*)a;}
int gcd(int x,int y){if(y==0)return x;return gcd(y,x%y);}
/*
int asc_t(const void *a,const void *b){return ((struct_t*)a)->member - ((struct_t*)b)->member;}
int desc_t(const void *a,const void *b){return ((struct_t*)b)->member - ((struct_t*)a)->member;}
*/
int main(){
    int n;
    int cnt=0;
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        if(i%2!=0){
            cnt++;
        }
    }
    printf("%.9lf\n",(double)cnt/(double)n);
    return 0;
}