1 #define bug(x) cout<<#x<<" is "<<x<<endl
2 #define IO std::ios::sync_with_stdio(0)
3 #include <bits/stdc++.h>
4 using namespace std;
5 #define ll long long
6 #define pb push_back
7 const ll mod=1e9+7;
8 const int N=2e5+10;
9
10 char s[N],t[N];
11
12 struct node{
13 int c;
14 node *lson,*rson;
15 };
16
17 int a[200],b[200],id[200],d[200],n,cnt;
18
19 node *root;
20
21 node* build(node *now){
22 now =new node();
23 //now=(node *)malloc(sizeof(node));
24 //now->lson=now->rson=NULL;
25 int k=id[s[cnt]];
26 d[k]=1;
27 now->c=s[cnt++];
28
29 if(k>1&&!d[k-1]){
30 now->lson=build(now->lson);
31 }
32 if(k<n&&!d[k+1]){
33 now->rson=build(now->rson);
34 }
35 return now;
36 }
37
38 void preorder(node *now){
39 if(now->lson!=NULL)preorder(now->lson);
40 if(now->rson!=NULL)preorder(now->rson);
41 printf("%c",now->c);
42 }
43
44 void work(){
45 preorder(build(root));
46 }
47
48 int main(){
49 scanf("%s",s+1);
50 scanf("%s",t+1);
51 n=strlen(s+1);
52
53 for(int i=1;i<=n;i++){
54 id[t[i]]=i;
55 }
56 work();
57 }
58 /*
59 ABCD
60 BADC
61 BDCA
62
63 1 2 4 5 3 6
64 4 2 5 1 6 3
65 4 5 2 6 3 1
66 */
