fun main(arr: Array<String>) {
    println(decode())
}

fun decode():String {
    val s = readLine()!!.toMutableList()
    val t = readLine()!!
    for(i in s.size - t.length downTo 0) {
        var isMatch = true
        for(j in t.indices) {
            if(s[j+i] == '?') {
                continue
            }
            if(t[j] != s[j+i]) {
                isMatch = false
                break
            }
        }
        if(isMatch) {
            for(j in t.indices) {
                s[i+j] = t[j]
            }
            return s.map { if(it == '?') 'a' else it }.joinToString("")
        }
    }
    return "UNRESTORABLE"
}
