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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TOPSIC
{
    partial class Program
    {
        static void Main(string[] args)
        {
          string H = Console.ReadLine();
            string ans = "Yes";

            if (H.Length < 2)
            {
                ans = "No";
                Console.WriteLine(ans);
                return;
            }

            for (int i = 0; i < H.Length; i++)
            {
                if (i % 2 == 0)
                {
                    if (H[i] != 'h')
                    {
                        ans = "No";
                        break;
                    }
                }
                else
                {
                    if (H[i] != 'i')
                    {
                        ans = "No";
                        break;
                    }
                }
            }

            
            Console.WriteLine(ans);

        }
    }
}