N = int(input())

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

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