import java.io.{BufferedReader, InputStreamReader}

object Main extends App {

  def isMatch(s:String, t:String, k:Int):Boolean = {
    for(i <- 0 until t.length) {
      if(t.charAt(i) != s.charAt(i+k) && s.charAt(i+k) != '?')
        return false
    }
    true
  }
  def construct(arr:Array[Char], t:String, k:Int):Unit = {
      for(i <- 0 until t.length) {
        arr(i+k) = t.charAt(i)
      }
  }

  val in = new BufferedReader(new InputStreamReader(System.in))
  val s, t = in.readLine

  val ans = {
    val arr = s.toCharArray
    var isMatched = false

    for(i <- 0 to s.length - t.length) {
      if(isMatch(s, t, i)) {
        isMatched = true
        construct(arr, t, i)
      }
    }

    if(isMatched) {
      for(i <- 0 until s.length) {
        if(arr(i) == '?') {
          arr(i) = 'a'
        }
      }
      arr.mkString
    }
    else "UNRESTORABLE"
  }

  println(ans)
}