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;

public class A {
    public static void Main(){
        string S = Console.ReadLine();
        char[] str = S.ToCharArray();
    
        bool isHitachi = true;
        if (S.Length%2 ==1)
        {
            isHitachi = false;
        }
        else
        {
        for (int i=0;i<S.Length;i+=2)
        {
            if (!((str[i]=='h')&&(str[i+1]=='i')))
            {
                isHitachi = false;
                break;
            }
        }
        }
        if (isHitachi) Console.WriteLine("Yes");
        else Console.WriteLine("No");
    }
}