n = int(input())
if n == 1:
    print(1)
    exit()
if n % 2==0:print(0.5)
else:print((n//2+1)/n) n = int(input()) n int(input()) int input() input if n == 1:
    print(1)
    exit() n == 1 n 1 print(1) print 1 exit() exit if n % 2==0:print(0.5)
else:print((n//2+1)/n) n % 2==0 n % 2 n 2 0 n = int(input()) int(input()) n
n = int(input())
if n == 1:
    print(1)
    exit()
if n % 2==0:print(0.5)
else:print((n//2+1)/n)