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: Runtime Error)

using System;
using System.Linq;
namespace atcoder {
    class Program {
        static void Main () {
            var A = new ReadLine ();
            var B = A.String ();
            var cnt = 0;
            var cnt2 = 0;
            for (int i = 0; i < B.Length; i+=2) {
                if (B[i] == 'h' && B[i + 1] == 'i') {
                    cnt += 1;
                }
                cnt2 += 2;
            }
        
            if (cnt2 == cnt*2) {
                Console.WriteLine ("Yes");
            }else{
                Console.WriteLine ("No");
            }
        }
    }

    class ReadLine {
        public int Number () {
            int vs = int.Parse (Console.ReadLine ());
            return vs;
        }
        public int[] Int () {

            int[] vs = Console.ReadLine ().Split (' ').Select (int.Parse).ToArray ();
            return vs;
        }
        public string String () {

            string vs = Console.ReadLine ();
            return vs;
        }
    }
}