use proconio::input;
use std::cmp::Ordering::{Equal, Greater, Less};

fn main() {
	input! {
		s: String,
		t: String,
	}

    let mut a = s.chars().filter_map(|c| c.to_digit(10));
    let mut b = t.chars().filter_map(|c| c.to_digit(10));

    for (x, y) in a.by_ref().zip(b.by_ref()) {
        match x.cmp(&y) {
            Equal => continue,
            Greater => {
            	println!("YES");
            	return;
            },
            Less => {
	            println!("NO");
	            return;
	        },
        }
    }

    println!("YES");
}