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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    public static void Main()
    {
        string s = Console.ReadLine();
        bool flag = false;

        if (s[0] != 'h')
        {
            flag = true;
        }
        for (int i = 1; i < s.Length; i++)
        {
            if (s[i] == 'i')
            {
                if (s[i - 1] != 'h')
                {
                    flag = true;
                }
            } else if (s[i] == 'h')
            {
                if (s[i - 1] != 'i')
                {
                    flag = true;
                }
            } else
            {
                flag = true;
            }
        }
        if (s.Length % 2 == 1)
        {
            flag = true;
        }

        if (flag)
        {
            Console.WriteLine("No");
        } else
        {
            Console.WriteLine("Yes");
        }
    }
}