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