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 Ruby (2.3.3) (judge verdict: Wrong Answer)

# 文字列 hi が 1 個以上繋がってできる文字列を、 hitachi文字列 と定義します。
# 例えば、 hi や hihi などは hitachi文字列 であり、 ha や hii は hitachi文字列 ではありません。
# 文字列 S が与えられるので、 S が hitachi文字列 かどうかを判定してください。

s = gets.chomp
result = true
i = 0
if s.length.even?
    loop do
        break if i+1 >= s.length
        if !(s[i] == "h" && s[i+1] == "i")
            result = false
            break
        end
        i += 2
    end
end

if result
    puts "Yes"
else
    puts "No"
end