1 #include <cstring>
 2 #include <iostream>
 3 #include <cstdio>
 4 using namespace std;
 5 string s1, s2;
 6 
 7 void calc(int l1, int r1, int l2, int r2)
 8 {
 9     int m = s2.find(s1[l1]);
10     if(m > l2) calc(l1 + 1, l1 + m - l2, l2, m - 1);
11     if(m < r2) calc(l1 + m - l2 + 1, r1, m + 1, r2);
12     cout << s1[l1];
13 }
14 
15 int main()
16 {
17     freopen("tree.in", "r", stdin);
18     freopen("tree.out", "w", stdout);
19     cin >> s1 >> s2;
20     calc(0, s1.length() - 1, 0, s2.length() - 1);
21     cout << endl;
22     return 0;
23 }