C Program to calculate depth of Tree

/* Height/Depth of a Tree */
#include<iostream.h>
#include<alloc.h>
#include<conio.h>
struct tree
{
       int item,level;
       struct tree *right,*left;
};
void create(struct tree *p)
{
     int choice;
     cout<<"\nEnter value";
     cin>>p->item;
     cout<<"\nDo you Want to Enter left Child of "<<p->item<<" .1.YES/2.NO";
     cin>>choice;
     if(choice==1)
     {
          p->left=(tree*)malloc(sizeof(tree));
          p->left->level=p->level+1;
          create(p->left);
     }
     else
     {
          p->left=NULL;
     }
     cout<<"Do you Want to Enter Right Child of  "<<p->item<<" .1.YES/2.NO";
     cin>>choice;
     if(choice==1)
     {
          p->right=(tree*)malloc(sizeof(tree));
          p->right->level=p->level+1;
          create(p->right);
     }
     else
     {
          p->right=NULL;
     }
}
static int max=0;
void findmax(tree *p)
{
  if(p==NULL)return;
  if(p->level>max)
  max=p->level;
  findmax(p->left);
  findmax(p->right);
}
int main()
{
     clrscr();
     struct tree *a;
     a=(tree*)malloc(sizeof(tree));
     a->level=0;
     cout<<"Enter Tree\n";
     create(a);
     findmax(a);
     cout<<"\nHeight of a Binary Tree is"<<max;
     getch();
     return 0;
}