#include<bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
typedef long long ll;
int main() {
  string s,t;
  cin >> s>>t;
  int diff=s.size()-t.size();
  for(int i=diff;i>=0;i--){
     int f=1;
     rep(j,t.size())
       if(s[i+j]!='?'&&s[i+j]!=t[j]){
          f=0;
          break; 
       }
     if(f){
        rep(j,i)
          cout<<(s[j]=='?'?'a':s[j]);
        cout<<t;
        for(int j=i+t.size();j<(int)s.size();j++)
          cout<<(s[j]=='?'?'a':s[j]);
        return 0;
     }
  }
  cout<<"UNRESTORABLE";
  return 0;
}