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

int main()
{
  string S, T;
  cin >> S >> T;
  string U;
  int i = S.size() - T.size();
  for (; 0 <= i; --i)
  {
    auto b = i + T.size();
    U = S.substr(0, i) + T + S.substr(b, S.size() - b);
    int j = 0;
    for (; j < S.size(); ++j)
      if ((S[j] != U[j]) && ('?' != S[j]))
        break;
    if (S.size() == j)
      break;
  }
  if (i < 0)
    cout << "UNRESTORABLE";
  else
  {
    for (int i = 0; i < U.size(); ++i)
      if ('?' == U[i])
        U[i] = 'a';
    cout << U;
  }
  return 0;
}
