int lev=0;
 6 void level(bitree *bt,int x)
 7 {
 8     if(bt!=null){ 
 9         lev++;
10         if(bt->key==x) return; 
11         else if(bt->key>x) level(bt->lchild,x); 
12         else level(bt->rchild,x);
13     }
14 }