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