n=int(input())
if n%2==0:
    print("0.5000000000")

if n%2==1:
    ans=(int(n/2)+1)/n
    print(ans) n=int(input()) n int(input()) int input() input if n%2==0:
    print("0.5000000000") n%2==0 n%2 n 2 0 print("0.5000000000") print "0.5000000000" if n%2==1:
    ans=(int(n/2)+1)/n
    print(ans) n%2==1 n%2 n 2 1 ans=(int(n/2)+1)/n ans (int(n/2)+1)/n int(n/2)+1 int(n/2) int n/2 n 2 1 n print(ans) print ans ans=(int(n/2)+1)/n (int(n/2)+1)/n ans n=int(input()) int(input()) n
n=int(input())
if n%2==0:
    print("0.5000000000")

if n%2==1:
    ans=(int(n/2)+1)/n
    print(ans)