n=int(input())
if n%2==0:
    print("0.5")
if n%2==1:
    print((int(n/2)+1)/n) n=int(input()) n int(input()) int input() input if n%2==0:
    print("0.5") n%2==0 n%2 n 2 0 print("0.5") print "0.5" if n%2==1:
    print((int(n/2)+1)/n) n%2==1 n%2 n 2 1 print((int(n/2)+1)/n) print (int(n/2)+1)/n int(n/2)+1 int(n/2) int n/2 n 2 1 n n=int(input()) int(input()) n
n=int(input())
if n%2==0:
    print("0.5")
if n%2==1:
    print((int(n/2)+1)/n)