fun main(args: Array<String>) {
    val s= readLine()!!
    val t= readLine()!!

    val x=(0 .. s.length-t.length).lastOrNull { i ->
        t.indices.all { t[it]==s[i+it] || s[i+it]=='?'}
    }
    if(x==null) {
        println("UNRESTORABLE")
    } else {
        println(
            (s.take(x) + t + s.drop(x + t.length)).replace('?','a')
        )
    }

}