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