# 問題：https://atcoder.jp/contests/abc142/tasks/abc142_a

n = int(input())
res = (n+1)//2
res /= n
print(res)
 n = int(input()) n int(input()) int input() input res = (n+1)//2 res (n+1)//2 n+1 n 1 2 res /= n res n print(res) print res res /= n n res res = (n+1)//2 (n+1)//2 res n = int(input()) int(input()) n
# 問題：https://atcoder.jp/contests/abc142/tasks/abc142_a

n = int(input())
res = (n+1)//2
res /= n
print(res)

