object Main{
  def ok(s:String,t:String) : Boolean = {
    if(s.length != t.length){
      return false
    }else{
      for(i <- 0 to s.length-1){
        if(s(i)!=t(i) && s(i)!='?') return false
      }
      true
    }
  }
  def gen(s:String,t:String,idx:Int) : String = {
    var sc = s.toCharArray
    for(i <- 0 to t.length-1) sc(idx+i) = t(i)
    for(i <- 0 to sc.length-1) if(sc(i) == '?') sc(i) = 'a'
    sc.mkString
  }


  def main(args:Array[String]) = {
    val sc = new java.util.Scanner(System.in)
    val s,t = sc.nextLine
    val n = s.length
    val m = t.length
    val end = "z" * 100

    val ar = for(i <- 0 to n-1) yield {
      val sub = s.slice(i,i+m)
      val isok = ok(sub,t)
      if(isok) gen(s,t,i)
      else end
    }
    val ans = ar.filter(x=>x.length>0).min
    if(ans.length <= 50) println(ans)
    else println("UNRESTORABLE")
  }
}
