#include <iostream>
#include <cstdio>
using namespace std;

string a, b, ans;
int main()
{
	int i, j, k;
	cin >> a >> b;
	for (i = a.size(); i >= 0; i--) {
		for (j = 0; j < b.size(); j++) {
			if (i + j >= a.size() || a[i + j] != b[j] && a[i + j] != '?') break;
		}
		if (j == b.size()) break;
	}
	if (i < 0) {
		cout << "UNRESTORABLE";
		return 0;
	}
	k = i;
	for (i = 0; i < a.size(); i++) {
		if (k <= i && i < k + b.size()) ans += b[i - k];
		else if (a[i] == '?') ans += 'a';
		else ans += a[i];
	}
	cout << ans;
    return 0;
}
