using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace yukicoderTest
{
    class Program
    {
        static void Main(string[] args)
        {
            string N = Console.ReadLine();
            string X = Console.ReadLine();
            N = N.Replace(".", "");
            X = X.Replace(".", "");
            for (int i = 0; i < N.Length; i++)
            {
                int ver = int.Parse(N.Substring(i, 1));
                int judge = int.Parse(X.Substring(i,1));

                if (judge < ver)
                {
                    Console.WriteLine("YES");
                    break;
                }
                else if (judge == ver) 
                {
                    continue;
                }
                else
                {
                    Console.WriteLine("NO");
                    break;
                }

            }
        }

    }
}