Function to find height of a tree
int height ( Node * root , int & ans , Node * ( & k ) , int & lh , int & rh , int & f ) { if ( root == NULL ) return 0 ; int left_height = height ( root -> left , ans , k , lh , rh , f ) ; int right_height = height ( root -> right , ans , k , lh , rh , f ) ;