Problem:
Score : 100 points

Problem Statement

A Hitachi string is a concatenation of one or more copies of the string hi.

For example, hi and hihi are Hitachi strings, while ha and hii are not.

Given a string S, determine whether S is a Hitachi string.

Constraints

The length of S is between 1 and 10 (inclusive).

S is a string consisting of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If S is a Hitachi string, print Yes; otherwise, print No.

Sample Input 1

hihi

Sample Output 1

Yes

hihi is the concatenation of two copies of hi, so it is a Hitachi string.

Sample Input 2

hi

Sample Output 2

Yes

Sample Input 3

ha

Sample Output 3

No

Solution in OCaml (4.02.3) (judge verdict: Wrong Answer)

let () =
  let s = Scanf.scanf "%s\n" @@ fun s -> s in
  let ans = ref true in
  for i = 0 to String.length s - 1 do
    if (i mod 2 = 0 && s.[i] = 'h') || (i mod 2 = 1 && s.[i] = 'i')
    then ans := !ans && true
    else ans := !ans && false
  done;
  Printf.printf "%s\n" (if !ans then "Yes" else "No")