#![allow(unused_imports)]

use std::cmp;
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::fmt;
use std::io::{self, BufWriter, Read, Write};
use std::ops::{Add, Div, Mul, Sub};
use std::str::{self, FromStr};


fn solve(s: String, t: String) -> Option<String> {
    let (s, t) = (s.as_bytes(), t.as_bytes());
    (0..s.len() - t.len() + 1)
        .rev()
        .filter_map(|i| {
            try_restoring(&s[..i], &s[i..t.len() + i], &s[t.len() + i..], t)
        })
        .next()
}


fn try_restoring(s1: &[u8], s2: &[u8], s3: &[u8], t: &[u8]) -> Option<String> {
    if s2.len() != t.len() {
        return None;
    }
    s2.iter()
        .zip(t.iter())
        .map(|(&c1, &c2)| match (c1, c2) {
            (c1, c2) if c1 == '?' as u8 || c1 == c2 => Some(c2),
            _ => None,
        })
        .fold(Some(Vec::with_capacity(t.len())), |r, c| match (r, c) {
            (Some(mut r), Some(c)) => {
                r.push(c);
                Some(r)
            }
            _ => None,
        })
        .map(|r| {
            let s1 = s1.iter().map(replace_with_a);
            let s3 = s3.iter().map(replace_with_a);
            String::from_utf8(s1.chain(r.into_iter()).chain(s3).collect::<Vec<_>>()).unwrap()
        })
}


fn replace_with_a(c: &u8) -> u8 {
    if *c == '?' as u8 { 'a' as u8 } else { *c }
}


fn main() {
    let stdin = io::stdin();
    let mut sc = Scanner::new(stdin.lock().bytes());
    match solve(sc.next(), sc.next()) {
        Some(x) => println!("{}", x),
        None => println!("UNRESTORABLE"),
    }
}


struct Scanner<R: Read> {
    buf: Vec<u8>,
    bytes: io::Bytes<R>,
}

#[allow(dead_code)]
impl<R: Read> Scanner<R> {
    fn new(bytes: io::Bytes<R>) -> Self {
        Scanner {
            buf: Vec::with_capacity(1024),
            bytes: bytes,
        }
    }

    fn next<T: FromStr>(&mut self) -> T
    where
        <T as FromStr>::Err: fmt::Debug,
    {
        let buf = &mut self.buf;
        buf.clear();
        self.bytes
            .by_ref()
            .map(Result::unwrap)
            .skip_while(|&c| c == ' ' as u8 || c == '\n' as u8)
            .take_while(|&c| !(c == ' ' as u8 || c == '\n' as u8))
            .foreach(|c| buf.push(c));
        str::from_utf8(&buf).unwrap().parse().unwrap()
    }

    fn vec<T: FromStr>(&mut self, n: usize) -> Vec<T>
    where
        <T as FromStr>::Err: fmt::Debug,
    {
        (0..n).map(|_| self.next()).collect()
    }

    fn pairs<T1: FromStr, T2: FromStr>(&mut self, n: usize) -> Vec<(T1, T2)>
    where
        <T1 as FromStr>::Err: fmt::Debug,
        <T2 as FromStr>::Err: fmt::Debug,
    {
        (0..n).map(|_| (self.next(), self.next())).collect()
    }

    fn trios<T1: FromStr, T2: FromStr, T3: FromStr>(&mut self, n: usize) -> Vec<(T1, T2, T3)>
    where
        <T1 as FromStr>::Err: fmt::Debug,
        <T2 as FromStr>::Err: fmt::Debug,
        <T3 as FromStr>::Err: fmt::Debug,
    {
        (0..n)
            .map(|_| (self.next(), self.next(), self.next()))
            .collect()
    }

    fn mat<T: FromStr>(&mut self, m: usize, n: usize) -> Vec<Vec<T>>
    where
        <T as FromStr>::Err: fmt::Debug,
    {
        (0..m).map(|_| self.vec(n)).collect()
    }
}


trait Foreach {
    type Item;
    fn foreach<F: FnMut(Self::Item)>(self, f: F);
}

impl<T, I: Iterator<Item = T>> Foreach for I {
    type Item = T;

    fn foreach<F: FnMut(T)>(self, mut f: F) {
        self.fold((), move |(), x| f(x));
    }
}


#[allow(dead_code)]
fn print_yesno(x: bool, yes: &'static str, no: &'static str) {
    println!("{}", if x { yes } else { no });
}


#[allow(dead_code)]
fn print_foreach<T: fmt::Display, I: IntoIterator<Item = T>>(xs: I) {
    let stdout = io::stdout();
    let mut stdout = BufWriter::new(stdout.lock());
    for x in xs.into_iter() {
        writeln!(stdout, "{}", x).unwrap();
    }
    stdout.flush().unwrap();
}


#[allow(dead_code)]
fn print_or<T: fmt::Display>(x: Option<T>, or: &'static str) {
    if let Some(x) = x {
        println!("{}", x);
    } else {
        println!("{}", or);
    }
}


Measured memory_bytes: 4352