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.Text.RegularExpressions;

namespace A {
    class Program {
        static void Main(string[] args) {
            var hiInf = new Regex(@"^hi{2,}");
            var regex = new Regex(@"^(hi)+$");
            var str = Console.ReadLine();

            if (hiInf.IsMatch(str)) {
                Console.WriteLine("No");
                return;
            }

            if (regex.IsMatch(str))
                Console.WriteLine("Yes");
            else
                Console.WriteLine("No");
            
        }
    }
}