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