Problem:
Score : 100 points

Problem Statement

Two deer, AtCoDeer and TopCoDeer, are playing a game called Honest or Dishonest.
In this game, an honest player always tells the truth, and an dishonest player always tell lies.
You are given two characters a and b as the input. Each of them is either H or D, and carries the following information:

If a=H, AtCoDeer is honest; if a=D, AtCoDeer is dishonest.
If b=H, AtCoDeer is saying that TopCoDeer is honest; if b=D, AtCoDeer is saying that TopCoDeer is dishonest.

Given this information, determine whether TopCoDeer is honest.

Constraints

a=H or a=D.

b=H or b=D.

Input

The input is given from Standard Input in the following format:

a b

Output

If TopCoDeer is honest, print H. If he is dishonest, print D.

Sample Input 1

H H

Sample Output 1

H

In this input, AtCoDeer is honest. Hence, as he says, TopCoDeer is honest.

Sample Input 2

D H

Sample Output 2

D

In this input, AtCoDeer is dishonest. Hence, contrary to what he says, TopCoDeer is dishonest.

Sample Input 3

D D

Sample Output 3

H

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Linq;
using System.Numerics;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;
using System.Text.RegularExpressions;

namespace CsTest
{
    class Program
    {
        static void Main()
        {
            var ab = AtCoder.ReadStringArray();
            var a = ab[0];
            var b = ab[1];

            Console.WriteLine(a == b ? 'H' : 'D');
        }
    }

    public class AtCoder
    {
        public static string[] ReadStringArray() => Console.ReadLine().Split(Array.Empty<char>(), StringSplitOptions.RemoveEmptyEntries);
        public static int[] ReadInt32Array() => ReadStringArray().Select(s => int.Parse(s)).ToArray();
        public static long[] ReadInt64Array() => ReadStringArray().Select(s => long.Parse(s)).ToArray();
    }
}