text: #include<cstdio>
  #include<cstring>
  #include"avlt.h"
  main()
  {
      bst<int> test;
      char cmd[1000];
      int i;
      while(1)
      {
          scanf("%s",cmd);
          if(!strcmp(cmd,"q"))
              break;
          if(!strcmp(cmd,"s"))
          {
              test.show();
              puts("");
              continue;
          }
          scanf("%d",&i);
          if(!strcmp(cmd,"f"))
          {
              printf("%d\n",test.nth(i));
          }
          if(!strcmp(cmd,"i"))
          {
              if(!test.find(i))
                  test.ins(i);
          }
          if(!strcmp(cmd,"d"))
          {
              if(test.find(i))
                  test.del(i);
          }
      }
  }
  