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