#include <iostream>
#include <string>

#define rep(i,n) for(int i = 0; i < n; i++)

using namespace std;

int main(){
  string sd, t;
  cin >> sd >> t;

  int f = -1;
  for(int i=sd.size()-t.size(); i>=0;i--){
    bool ok = true;
    rep(j,t.size()){
      if(sd[i+j] != t[j] && sd[i+j] != '?'){
	ok = false;
      }
    }
    if(ok){
      f = i;
      break;
    }
  }
  if(f == -1) cout << "UNRESTORABLE" << endl;
  else{
    rep(i,t.size()){
      sd[f+i] = t[i];
    }
    rep(i,sd.size()){
      if(sd[i] == '?') sd[i] = 'a';
    }
    cout << sd << endl;
  }
}
