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 s = read_line () in
let n = String.length s in
let rec loop i =
    if i = n then true else (
        match i mod 2, s.[i] with
        | 0, 'h'
        | 1, 'i' -> loop (i + 1)
        | _ -> false
    )
in
(if loop 0 then "Yes" else "No") |> print_endline