// A binary tree node

static class Node {

int data;

Node left, right;

Node(int item) {

data = item;

left = right = null;

}

}

Node root;

// Function to insert a new node with given key in BST

static Node insert(Node node, int key, Wrapper succ) {

// If the tree is empty, return a new node

if (node == null) {

return new Node(key);

}

// If key is smaller than node's key, go to left subtree

if (key < node.data) {

succ.node = node; // Update successor

node.left = insert(node.left, key, succ);

}

// If key is greater than or equal to node's key, go to right subtree

else {

node.right = insert(node.right, key, succ);

}

return node;

}

// Wrapper class to hold successor node

static class Wrapper {

Node node;

}

// Function to replace every element with the least greater element on its right

static void replaceWithLeastGreater(int[] arr) {

Node root = null;

// Traverse the array from right to left

for (int i = arr.length - 1; i >= 0; i--) {

Wrapper succ = new Wrapper();

root = insert(root, arr[i], succ);

// Replace arr[i] with its successor if it exists

arr[i] = (succ.node != null) ? succ.node.data : -1;

}

}

// Driver method to test above methods

public static void main(String args[]) {

int[] arr = {8, 58, 71, 18, 31, 32, 63, 92, 43, 3, 91, 93, 25, 80, 28};

replaceWithLeastGreater(arr);

System.out.println("Modified array:");

for (int value : arr) {

System.out.print(value + " ");

}

}

}