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 Program2
{
    static void Main(string[] args)
    {
        string _strinput = Console.ReadLine();
        string[] _stringh = _strinput.Split((char)105);
        string[] _stringi = _strinput.Split((char)104);
        if ((_strinput.Length % 2) != 0 || _strinput == "")
        {
            Console.WriteLine("No");
            return;
        }
        else if (_stringh.Length != _stringi.Length) {
            Console.WriteLine("No");
            return;
        }

        for(int i1 = 0; i1< _stringh.Length -1; i1++) {
            if (_stringh[i1] != "h") {
                Console.WriteLine("No");
                return;
            }
        }
        if (_stringh[_stringh.Length - 1] != "")
        {
            Console.WriteLine("No");
            return;
        }
        for (int i2 = 1; i2 < _stringi.Length ; i2++)
        {
            if (_stringi[i2] != "i")
            {
                Console.WriteLine("No");
                return;
            }
        }
        if (_stringi[0] != "")
        {
            Console.WriteLine("No");
            return;
        }
        Console.WriteLine("Yes");
        

    }
}