#include<stdio.h>
#include<stdlib.h>
#include<string.h>
struct node
{
char data;
struct node *lchild,*rchild;
};
char a[55];
int i;
struct node *creat()
{
struct node *t;
char e;
e = a[i++];//是否可以直接替换成 if(s[i++] == ‘,’) return NULL;
if(e==’,’)return t = NULL;
else
{
t = (struct node *)malloc(sizeof(struct node));
t -> data = e;
t -> lchild = creat();
t -> rchild = creat();
}
return t;
}
void output(struct node *t)
{
int i = 0,j = 1;
int flag;
struct node *b[55];//建立结构体数组
b[0] = t;
while(i < j)//是否等同于层次遍历
{
if(b[i])
{
flag = 0;
b[j++] = b[i] -> lchild;
if(b[i]->lchildNULL)flag++;//若结点不为空,则下一个数组元素存左孩子
b[j++] = b[i] -> rchild;//存右孩子的地址;
if(b[i]->rchildNULL)flag++;
if(flag==2)printf("%c",b[i]->data);//若左右孩子都为空,则为叶子,输出次结点
}
i++;
}
}
int main()
{
while(~scanf("%s",a))
{
struct node *T;
i = 0;
T = creat();
output(T);
printf("\n");
}
return 0;
}