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

string s,t;

bool search(int x){
  for(int i = 0;i < t.size();i++){
    if(!(s[i+x] == t[i] || s[i+x] == '?')){
      return false;
    }
  }

  return true;
}


int main(){
  cin >> s >> t;

  for(int i = s.size()-t.size();i >= 0;i--){
    if(search(i)){
      for(int j = 0;j < s.size();j++) if(s[j] == '?') s[j] = 'a';
      for(int j = 0;j < t.size();j++){
        s[i+j] = t[j];
      }
      cout << s << endl;
      return 0;
    }
  }

  cout << "UNRESTORABLE" << endl;
  return 0;
}
