#define _LIBCPP_DEBUG 0
#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=int(a);i<int(b);i++)
typedef vector<int> vi;
typedef long long ll;


int main(){
    string s,t;cin>>s>>t;
    int pos=-1,ok=1;
    rep(i,0,s.size()-t.size()+1){
        ok=1;
        rep(j,0,t.size()){
            if(s[i+j]!=t[j]&&s[i+j]!='?')ok=0;
        }
        if(ok==1)pos=i;
    }
    rep(j,pos,pos+t.size()){
        s[j]=t[j-pos];
    }
    rep(i,0,s.size())if(s.at(i)=='?')s.at(i)='a';
    
    if(pos!=-1)cout<<s<<endl;
    else cout<<"UNRESTORABLE"<<endl;
}




