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 N = int(input()) int(input()) N
N = int(input())

if N % 2 == 0: print(0.5)
else: print((N+1)/(2*N))