#include <iostream>
#include <string>
using namespace std;
int main(){
	string sd;
	cin>>sd;
	
	string t;
	cin>>t;
	
	size_t n=sd.size();
	size_t m=t.size();
	string s;
	bool isCan;
	for(int i=n-m;i>=0;--i){
		s=sd;
		for(int j=0;j<m;++j){
			isCan = true;
			if(sd[i+j]=='?' or t[j]==sd[i+j]){
			  s[i+j] = t[j];
			}else{
				isCan=false;
				break;
		    }
		}
		if(isCan)
		  break;
	}
	if(isCan){
	for(auto& i : s){
		if(i=='?') i='a';
	}
	cout<< s << endl;
	}else{
		cout<<"UNRESTORABLE"<<endl;
    }
	return 0;
}