#include<iostream>
#include<string>
using namespace std;

int main()
{
    string s1,s2;
    cin >> s1 >> s2;
    int flag=1;
    for(int i=0; i<s1.length(); i+=2) {
        if(s1[i] >= s2[i]) { continue;}
        else { flag=0; break;}
    }
    if(flag==0) { cout << "NO" << endl; }
    else if(flag==1) { cout << "YES" << endl;}
    return 0;
}