#include <bits/stdc++.h>
#include <atcoder/all>
// using mint = atcoder::static_modint<998244353>;
// //using mint = atcoder::static_modint<1000000007>;
using namespace std;
using namespace atcoder;
using ld = long double;
using ll = long long;
#define mp(a,b) make_pair(a,b)
#define rep(i,s,n) for(int i=s; i<(int)n; i++)
const vector<int> dx{1,0,-1,0},dy{0,1,0,-1};

int main(){
    string s,t;cin >> s >> t;
    int n=s.size(),m=t.size();
    if(n==m){
        rep(i,0,n)cout << s[i] << t[i];
    }
    else if(n==m+1){
        rep(i,0,m)cout << s[i] << t[i];
        cout << s.back();
    }
    else cout << "!";
}