#include <stdio.h>  
#include <stdlib.h>  
typedef struct TreeNode  
{  
    char    data;  
    struct TreeNode   *lchild;  
    struct TreeNode   *rchild;  
} Node, *PNode;  
  
char     preorder[28];   //存放前序序列  
char     infix[28];  //存放中序序列  
char    *Pr;  
  
void build(char *in, char *pr, PNode *tr);  
void postordertraversal(PNode T);  
  
int main()  
{  
    //先建树、再后序遍历输出  
    PNode    T;  
      
    while(scanf("%s %s", &preorder[1], &infix[1]) == 2)  
    {  
        build(&infix[1], &preorder[1], &T);  
        postordertraversal(T);  
        printf("\n");  
    }  
    return    0;  
}  
  
void build(char *in, char *pr, PNode *tr)  
{  
    char    *p = in;  
    Pr = pr;  
    if (*in == 0)  
    {  
        *tr = NULL;  
        return;  
    }  
    while (1)  
    {  
        if (*in == *Pr)  
        {  
            (*tr) = (PNode)malloc(sizeof(Node));  
            (*tr)->data = *Pr;  
            *in = 0;  
            break;  
        }  
        in++;  
    }  
    Pr = Pr + 1;  
    build(p, Pr, &(*tr)->lchild);  
    build(in+1, Pr, &(*tr)->rchild);  
}  
  
void postordertraversal(PNode T)  
{  
    if (T == NULL)  
        return;  
    postordertraversal(T->lchild);  
    postordertraversal(T->rchild);  
    printf("%c", T->data);  
}