// C++ solution code goes here
struct Node
{
	int key;
	struct Node *left;
	struct Node *right;
	
	Node(int x){
	    key = x;
	    left = NULL;
	    right = NULL;
	}
};
*/

// This function finds predecessor and successor of key in BST.
// It sets pre and suc as predecessor and successor respectively
class Solution
{
    public:
    void findSuccessor(Node* root, Node*& s, int key)
    {
        if(!root)
        {
            s == nullptr;
            return;
        }
        
        Node* cur = root;
        while(cur)
        {
            if(cur->key <= key)
            {
                cur = cur->right;
            }
            else
            {
                s = cur;
                cur = cur->left;
            }
        }
    }
    
    void findPredecessor(Node* root, Node* &p, int key)
    {
        if(!root)
        {
            p = nullptr;
            return;
        }
        Node* cur = root;
        while(cur)
        {
            if(cur->key >= key)
                cur = cur->left;
            else
            {
                p = cur;
                cur = cur->right;
            }
        }
    }
    
    void findPreSuc(Node* root, Node*& pre, Node*& suc, int key)
    {
        // Your code goes here
        findSuccessor(root, suc, key);
        findPredecessor(root, pre, key);
    }
};
        

            // Java solution code goes here
        

        # Python solution code goes here