C++ :

#include<stdio.h>
#include<string.h>
#define MAXN 30
char s1[MAXN],s2[MAXN],ans[MAXN];
void build(int n,char *s1,char *s2,char *s)
{   int p;
    if(n<=0) return ;
    p=strchr(s2,s1[0])-s2;
    build(p,s1+1,s2,s);
    build(n-p-1,s1+p+1,s2+p+1,s+p);
    s[n-1]=s1[0];
}
int main(void)
{
    int n;
    scanf("%s%s",s1,s2);
    n=strlen(s1);
    build(n,s2,s1,ans);
    ans[n]='\0';
    printf("%s\n",ans);
    return 0;
}

Pascal :

begin
  
  
end.