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 Rust (1.15.1) (judge verdict: Accepted)

#[allow(dead_code)]
fn scan<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn scan_split<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split_whitespace()
        .map(|t| t.parse().ok().unwrap()).collect()
}

#[allow(dead_code)]
fn scan_split_with<T: std::str::FromStr>(ch: char) -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split(ch)
        .map(|t| t.parse().ok().unwrap()).collect()
}

#[allow(dead_code)]
fn scan_lines<T: std::str::FromStr>(n: usize) -> Vec<T> {
    (0..n).map(|_| scan::<T>()).collect()
}

#[allow(unused_macros)]
macro_rules! scan_as_tuple {
    ( $t:ty ) => {
        (scan::<$t>(),)
    };
    ( $( $t:ty ),* ) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).ok();
            let v = s.trim().split_whitespace();
            let mut it = v;
            let ret = ( $(it.next().unwrap().parse::<$t>().ok().unwrap()),* );
            assert!(it.next() == None, "not all tokens consumed");
            ret
        }
    };
}

fn main() {
    let (s, t) = scan_as_tuple![String, String];
    println!("{}", if s == t { "H" } else { "D" });
}