#include<bits/stdc++.h> using namespace std; int main(){ char a[1001],b[1001]; cin>>a>>b; int c=strlen(a),d=strlen(b); if(c!=d){ cout<<"no"; } for(int i=0;i<c;i++){ if(a[i]==b[i]){ continue; }else{ break; } } cout<<"yes"; return 0; }