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;

class Program
{
    static void Main(string[] args)
    {
        string s = Console.ReadLine();

        const string hitachiChars = "hi";

        int count = 0;
        int strLength = s.Length;
        string result = "No";

        if (strLength % 2 == 0)
        {
            while(count < strLength)
            {
                string str = s.Substring(count,2);
                if(str != hitachiChars) {
                    break;
                }
                count += 2;
            }
            if (count == strLength)
            {
                result = "Yes";
            } 
        }    
        Console.WriteLine(result);
    }
}