#142-A

N = int(input())

D = []

for i in range(1,N+1):
    D.append(i)

#print(D)

cnt = 0

for j in D:
    if j % 2 != 0:
        cnt += 1


#print(cnt)
print(cnt / len(D))     N = int(input()) N int(input()) int input() input D = [] D [] for i in range(1,N+1):
    D.append(i)

#print(D) i range(1,N+1) range 1 N+1 N 1 D.append(i) D.append D append i cnt = 0 cnt 0 for j in D:
    if j % 2 != 0:
        cnt += 1


#print(cnt) j D if j % 2 != 0:
        cnt += 1


#print(cnt) j % 2 != 0 j % 2 j 2 0 cnt += 1 cnt 1 print(cnt / len(D)) print cnt / len(D) cnt len(D) len D N = int(input()) int(input()) N cnt += 1 1 cnt D = [] [] D cnt = 0 0 cnt
#142-A

N = int(input())

D = []

for i in range(1,N+1):
    D.append(i)

#print(D)

cnt = 0

for j in D:
    if j % 2 != 0:
        cnt += 1


#print(cnt)
print(cnt / len(D))    
