Problem: This is an interactive problem.

You are given a sorted in increasing order singly linked list. You should find the minimum integer in the list which is greater than or equal to x.

More formally, there is a singly liked list built on an array of n elements. Element with index i contains two integers: valuei is the integer value in this element, and nexti that is the index of the next element of the singly linked list (or -1, if the current element is the last). The list is sorted, i.e. if nexti ≠ - 1, then valuenexti > valuei.

You are given the number of elements in the list n, the index of the first element start, and the integer x.

You can make up to 2000 queries of the following two types:

  * ? i (1 ≤ i ≤ n) — ask the values valuei and nexti, 
  * ! ans — give the answer for the problem: the minimum integer, greater than or equal to x, or ! -1, if there are no such integers. Your program should terminate after this query. 



Write a program that solves this problem.

Input

The first line contains three integers n, start, x (1 ≤ n ≤ 50000, 1 ≤ start ≤ n, 0 ≤ x ≤ 109) — the number of elements in the list, the index of the first element and the integer x.

Output

To print the answer for the problem, print ! ans, where ans is the minimum integer in the list greater than or equal to x, or -1, if there is no such integer.

Interaction

To make a query of the first type, print ? i (1 ≤ i ≤ n), where i is the index of element you want to know information about.

After each query of type ? read two integers valuei and nexti (0 ≤ valuei ≤ 109,  - 1 ≤ nexti ≤ n, nexti ≠ 0).

It is guaranteed that if nexti ≠ - 1, then valuenexti > valuei, and that the array values give a valid singly linked list with start being the first element.

Note that you can't ask more than 1999 queries of the type ?.

If nexti = - 1 and valuei = - 1, then it means that you asked more queries than allowed, or asked an invalid query. Your program should immediately terminate (for example, by calling exit(0)). You will receive "Wrong Answer", it means that you asked more queries than allowed, or asked an invalid query. If you ignore this, you can get other verdicts since your program will continue to read from a closed stream.

Your solution will get "Idleness Limit Exceeded", if you don't print anything or forget to flush the output, including the final answer.

To flush you can use (just after printing a query and line end):

  * fflush(stdout) in C++; 
  * System.out.flush() in Java; 
  * stdout.flush() in Python; 
  * flush(output) in Pascal; 
  * For other languages see documentation. 



Hacks format

For hacks, use the following format:

In the first line print three integers n, start, x (1 ≤ n ≤ 50000, 1 ≤ start ≤ n, 0 ≤ x ≤ 109).

In the next n lines print the description of the elements of the list: in the i-th line print two integers valuei and nexti (0 ≤ valuei ≤ 109,  - 1 ≤ nexti ≤ n, nexti ≠ 0).

The printed structure should be a valid singly linked list. In particular, it should be possible to reach all elements from start by following links nexti, and the last element end should have -1 in the nextend.

Example

Input

5 3 80
97 -1
58 5
16 2
81 1
79 4


Output

? 1
? 2
? 3
? 4
? 5
! 81

Note

You can read more about singly linked list by the following link: <https://en.wikipedia.org/wiki/Linked_list#Singly_linked_list>

The illustration for the first sample case. Start and finish elements are marked dark. <image>

Solution (in JAVA):

Solution:
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Iterator;
import java.util.PriorityQueue;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.TreeSet;
import java.awt.PageAttributes.OriginType;
import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskC solver = new TaskC();
		solver.solve(1, in, out);
		out.close();
	}

	static class TaskC {
		private InputReader in;
		private PrintWriter out;
		private int x;
		private int numberOfQueries = 0;
		private int randomizationFactor = 100;
		private int maxQueries = 1999;

		private class LinkedListNode {
			private LinkedListNode[] linkedList;
			private int index;
			public int value = -1;
			private LinkedListNode next = null;
			private boolean isValid = false;

			public LinkedListNode(int index, LinkedListNode[] linkedList) {
				this.index = index;
				this.linkedList = linkedList;
			}

			public void makeValid() {
				if (isValid || value > x || numberOfQueries + 1 >= maxQueries) {
					return;
				}
				isValid = true;
				out.println("? " + (index + 1));
				out.flush();
				numberOfQueries++;
				value = in.nextInt();

				int nextIndex = in.nextInt() - 1;
				if (nextIndex >= 0) {
					next = linkedList[nextIndex];
					if (!next.isValid) {
						next.value = value + 1;
					}
				}
			}

			public void forceValidate() {
				isValid = true;
				out.println("? " + (index + 1));
				out.flush();
				value = in.nextInt();

				int nextIndex = in.nextInt() - 1;
				if (nextIndex >= 0) {
					next = linkedList[nextIndex];
					if (!next.isValid) {
						next.value = value + 1;
					}
				}
			}

			public LinkedListNode getNext() {
				return next;
			}

			public int getValueOrDefault(int defaultValue) {
				if (isValid) {
					return value;
				}
				return defaultValue;
			}

			public void printAsAnswer() {
				out.println("! " + value);
			}
		}

		private void swap(int[] a, int i, int j) {
			int temp = a[i];
			a[i] = a[j];
			a[j] = temp;
		}

		private void randomizeArrayFromIndex(int[] a, int index) {
			Random r = new Random();
			for (int k = 0; k < randomizationFactor; k++) {
				for (int i = index; i < a.length; i++) {
					int j = r.nextInt(a.length - index) + index;
					swap(a, i, j);
				}
			}
		}

		private void makeValidUntilSuspectFoundOrMaxQueriesExceeded(LinkedListNode[] linkedList, int[] queries,
				int minQueries) {
			int i = 0;
			while (i < queries.length && numberOfQueries + 1 <= minQueries) {
				linkedList[queries[i++]].makeValid();
			}
		}

		private LinkedListNode findClosestSmallerOrEqualElementToX(LinkedListNode[] linkedList) {
			LinkedListNode closestNodeFound = null;
			int closestNodeFoundValue = Integer.MIN_VALUE;
			for (LinkedListNode node : linkedList) {
				int nodeValue = node.getValueOrDefault(Integer.MIN_VALUE);
				if (nodeValue <= x && nodeValue > closestNodeFoundValue) {
					closestNodeFound = node;
					closestNodeFoundValue = nodeValue;
				}
			}
			return closestNodeFound;
		}

		private void validateEveryNodeAfterThisNodeUntillEndOrMaxQueries(LinkedListNode linkedListNode) {
			while (linkedListNode != null) {
				linkedListNode.makeValid();
				linkedListNode = linkedListNode.getNext();
			}
		}

		private LinkedListNode findClosestBiggerOrEqualElementToX(LinkedListNode[] linkedList) {
			LinkedListNode closestNodeFound = null;
			int closestNodeFoundValue = Integer.MAX_VALUE;
			for (LinkedListNode node : linkedList) {
				int nodeValue = node.getValueOrDefault(Integer.MAX_VALUE);
				if (nodeValue >= x && nodeValue < closestNodeFoundValue) {
					closestNodeFound = node;
					closestNodeFoundValue = nodeValue;
				}
			}
			return closestNodeFound;
		}

		public void solve(int testNumber, InputReader in, PrintWriter out) {
			this.in = in;
			this.out = out;

			int n = in.nextInt();
			int start = in.nextInt() - 1;
			this.x = in.nextInt();
			numberOfQueries = 0;

			LinkedListNode[] linkedList = new LinkedListNode[n];
			int[] queries = new int[n];
			for (int i = 0; i < n; i++) {
				queries[i] = i;
				linkedList[i] = new LinkedListNode(i, linkedList);
			}
			swap(queries, 0, start);
			randomizeArrayFromIndex(queries, 1);
			makeValidUntilSuspectFoundOrMaxQueriesExceeded(linkedList, queries, 1000);
			LinkedListNode closestListNode = findClosestSmallerOrEqualElementToX(linkedList);
			validateEveryNodeAfterThisNodeUntillEndOrMaxQueries(closestListNode);
			closestListNode = findClosestBiggerOrEqualElementToX(linkedList);
			if (closestListNode == null) {
				out.println("! " + "-1");
			} else {
				closestListNode.forceValidate();
				closestListNode.printAsAnswer();
			}
			out.flush();
		}
	}

	static class InputReader {
		public BufferedReader reader;
		public StringTokenizer tokenizer;

		public InputReader(InputStream stream) {
			reader = new BufferedReader(new InputStreamReader(stream), 32768);
			tokenizer = null;
		}

		public String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}

		public long nextLong() {
			return Long.parseLong(next());
		}

		public double nextFloat() {
			return Double.parseDouble(next());
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}

	}
}