public static void main(String[] args) {

    Scanner sc=new Scanner(System.in);
    String A=sc.next();
    String B=sc.next();
    int addition = A.length() + B.length();
    int number1 = 0;
    int number2 = 0;
    String[] Alphabet = new String[]{"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"};
    for (int j = 0; j < 25; j++) {
        if (A.substring(0) == Alphabet[j]){
            number1 = j;
            break;
        }
    }
    for (int j = 0; j < 25; j++) {
        if (B.substring(0) == Alphabet[j]){
            number2 = j;
            break;
        }
    }
    if (number1 > number2) {
        System.out.println("Yes");
    }
    else {
        System.out.println("No");
    }
}