#include<stdio.h>
#include<stdlib.h>
typedef int elemtype;
typedef struct node
{ elemtype data;
  struct node *lchild,*rchild;
 }BTNode,*BTree;
BTree CreateBTree(BTree &T)
{
    int number;
    if(number!=0)
    {scanf("%d",&number);
        T=(BTNode*)malloc(sizeof(BTNode));      
        T->data=number;
        CreateBTree(T->lchild);  
        CreateBTree(T->rchild);   
 }
}
int MAX(BTree BT)
{int m;
if(BT!=NULL)
m=BT->data;
if(BT->data>m)
m=BT->data;
MAX(BT->lchild);
MAX(BT->rchild);
return m;
}
void main()
{BTree T;
int n;
CreateBTree(T);
n=MAX(T);
printf("%d",n);
}