#include <bits/stdc++.h>
using namespace std;

signed main(){
    int a,b,c;char k;cin>>a>>k>>b>>k>>c;
    int A=a*1000000+b*10000+c;
    cin>>a>>k>>b>>k>>c;
    cout<<(a*1000000+b*10000+c>A?"NO":"YES")<<endl;;
}