// -*- coding:utf-8-unix -*-
// #![feature(map_first_last)]
#![allow(dead_code)]
#![allow(unused_imports)]
#![allow(unused_macros)]
// use core::num;
use std::cmp::*;
use std::fmt::*;
use std::hash::*;
use std::io::BufRead;
use std::iter::FromIterator;
use std::*;
use std::{cmp, collections, fmt, io, iter, ops, str};
const INF: i64 = 1223372036854775807;
const UINF: usize = INF as usize;
const LINF: i64 = 2147483647;
const INF128: i128 = 1223372036854775807000000000000;
const MOD1: i64 = 1000000007;
const MOD9: i64 = 998244353;
const MOD: i64 = MOD9;
// const MOD: i64 = MOD2;
const UMOD: usize = MOD as usize;
const M_PI: f64 = 3.14159265358979323846;

// use proconio::input;
// const MOD: i64 = INF;

use cmp::Ordering::*;
use std::collections::*;

use std::io::stdin;
use std::io::stdout;
use std::io::Write;

macro_rules! p {
    ($x:expr) => {
        //if expr
        println!("{}", $x);
    };
}

macro_rules! vp {
    // vector print separate with space
    ($x:expr) => {
        println!(
            "{}",
            $x.iter()
                .map(|x| x.to_string())
                .collect::<Vec<_>>()
                .join(" ")
        );
    };
}

macro_rules! d {
    ($x:expr) => {
        eprintln!("{:?}", $x);
    };
}
macro_rules! yn {
    ($val:expr) => {
        if $val {
            println!("Yes");
        } else {
            println!("No");
        }
    };
}

macro_rules! map{
    // declear btreemap
    ($($key:expr => $val:expr),*) => {
        {
            let mut map = ::std::collections::BTreeMap::new();
            $(
                map.insert($key, $val);
            )*
            map
        }
    };
}

macro_rules! set{
    // declear btreemap
    ($($key:expr),*) => {
        {
            let mut set = ::std::collections::BTreeSet::new();
            $(
                set.insert($key);
            )*
            set
        }
    };
}

//input output
#[allow(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[allow(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

#[allow(dead_code)]
fn read_mat<T: std::str::FromStr>(n: usize) -> Vec<Vec<T>> {
    (0..n).map(|_| read_vec()).collect()
}

#[allow(dead_code)]
fn readii() -> (i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1])
}

#[allow(dead_code)]
fn readiii() -> (i64, i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1], vec[2])
}
#[allow(dead_code)]
fn readuu() -> (usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1])
}

#[allow(dead_code)]
fn readff() -> (f64, f64) {
    let mut vec: Vec<f64> = read_vec();
    (vec[0], vec[1])
}

fn readcc() -> (char, char) {
    let mut vec: Vec<char> = read_vec();
    (vec[0], vec[1])
}

fn readuuu() -> (usize, usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1], vec[2])
}
#[allow(dead_code)]
fn readiiii() -> (i64, i64, i64, i64) {
    let mut vec: Vec<i64> = read_vec();
    (vec[0], vec[1], vec[2], vec[3])
}

#[allow(dead_code)]
fn readuuuu() -> (usize, usize, usize, usize) {
    let mut vec: Vec<usize> = read_vec();
    (vec[0], vec[1], vec[2], vec[3])
}

fn calc_mex(freq: &BTreeMap<u64, usize>, mut x: u64) -> u64 {
    while freq.get(&x).cloned().unwrap_or(0) > 0 {
        x += 1;
    }
    x
}

fn solve() {
    let n: usize = read();
    let mut x: Vec<usize> = read_vec();
    let mut contain = BTreeSet::new();
    for i in 0..n {
        contain.insert(x[i]);
    }
    let mut not_contain_val = 0;
    for i in 1..=n {
        if !contain.contains(&i) {
            not_contain_val = i;
            break;
        }
    }
    let mut pos_1 = 0;
    let mut pos_n = 0;
    let mut pos_n_minus_1 = 0;
    for i in 0..n {
        if x[i] == n {
            pos_n = i;
        }
        if x[i] == n - 1 {
            pos_n_minus_1 = i;
        }
        if x[i] == 1 {
            pos_1 = i;
        }
    }
    if not_contain_val != 0 {
        println!("? {} {}", not_contain_val, n);
        let ret: usize = read();
        if ret == 0 {
            p!("! A");
        } else {
            p!("! B");
        }
    } else {
        println!("? {} {}", 1, 2);
        let ret1: usize = read();
        println!("? {} {}", 2, 3);
        let ret2: usize = read();
        if ret1 == 0 || ret2 == 0 {
            println!("! A");
        } else if ret1 < n && ret2 < n {
            println!("! A");
        } else {
            println!("! B");
        }
    }

    return;
}
fn main() {
    let x = read::<String>();
    let y = read::<String>();

    if x.len() == y.len() || x.len() == y.len() + 1 {
        let mut s = String::new();
        let mut xc = x.chars();
        let mut yc = y.chars();

        while let Some(c) = xc.next() {
            s.push(c);
            if let Some(d) = yc.next() {
                s.push(d);
            }
        }

        p!(s);
    } else {
        p!("?");
    }
}