N = int(input())
print((N+1)//2/N) N = int(input()) N int(input()) int input() input 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())
print((N+1)//2/N)