#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef struct NodeTag{
char *Symbol;
struct NodeTag *LLink;
struct NodeTag *RLink;
}TreeNode;
TreeNode *Tree (TreeNode *A, char *S){
[code:1]if(A==NULL){
A=(TreeNode *)malloc(sizeof(TreeNode));
A->Symbol=(char *)malloc(strlen(S)+1);
A->LLink=NULL;
A->RLink=NULL;
A->Symbol=S;
}else if(strcmp(S,A->Symbol)<0){
A->LLink=Tree(A->LLink,S);