import scala.io.StdIn

object Main extends App {

  var ss = StdIn.readLine()
  val t = StdIn.readLine()
  var replaced = false

  def solve(i: Int): String = {
    if (i == -1) {
      ss
    } else {
      var k = 0
      while (k < t.length && 0 <= i - k && (ss(i - k) == t(t.length - k - 1) || ss(i - k) == '?')) {
        k += 1
      }
      if (k == t.length) {
        replaced = true
        val idx = i + 1 - k
        //println(s"idx: $idx")
        ss.take(idx) + t + ss.drop(idx + k)
      } else {
        solve(i - 1)
      }
    }
  }

  val r = solve(ss.length - 1)
  println(if (!replaced) "UNRESTORABLE" else r.replace("?", "a"))

}