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.*;
import java.util.*;

public class B {

	interface Interactor {
		int[] ask(int idx);

		void answer(int ans);

		int[] readInput();
	}

	static final int B = 1_000_000_000;

	static final int MAX_QUERIES = 1999;

	class SubmitInteractor implements Interactor {

		@Override
		public int[] ask(int idx) {
			out.println("? " + (idx + 1));
			out.flush();
			int[] ret = new int[2];
			ret[0] = nextInt();
			ret[1] = nextInt() - 1;
			if (ret[1] == -2) {
				ret[1] = -1;
			}
			return ret;
		}

		@Override
		public void answer(int ans) {
			out.println("! " + ans);
			out.flush();
		}

		@Override
		public int[] readInput() {
			int[] ret = new int[3];
			ret[0] = nextInt();
			ret[1] = nextInt() - 1;
			ret[2] = nextInt();
			return ret;
		}
		
	}
	
	class LocalInteractor implements Interactor {

		int n;
		int x;
		int[] arr;
		int qry;

		public LocalInteractor(int n) {
			this.n = n;
			arr = new int[n];
			HashSet<Integer> used = new HashSet<>();
			for (int i = 0; i < n; i++) {
				while (true) {
					arr[i] = rand(0, B);
					if (!used.contains(arr[i])) {
						used.add(arr[i]);
						break;
					}
				}
			}
			Arrays.sort(arr);
			x = -1;
			while (true) {
				x = rand(0, B);
				if (!used.contains(x)) {
					break;
				}
			}
			
			int[] perm = new int[n];
			for (int i = 0; i < n; i++) {
				int j = rand(0, i);
				perm[i] = perm[j];
				perm[j] = i;
			}
			
			
			
		}

		@Override
		public int[] ask(int idx) {
			if (idx < 0 || idx >= n) {
				throw new AssertionError("Bad query");
			}
			if (++qry > MAX_QUERIES) {
				throw new AssertionError("Too many queries");
			}
			return new int[] { arr[idx], idx == n - 1 ? -1 : idx + 1 };
		}

		@Override
		public void answer(int ans) {
			if (++qry > MAX_QUERIES) {
				throw new AssertionError("Too many queries");
			}
			int realAns = -1;
			for (int i = 0; i < n; i++) {
				if (arr[i] >= x) {
					realAns = arr[i];
					break;
				}
			}
			if (ans != realAns) {
				throw new AssertionError("WA");
			}
			System.err.println("OK " + qry + " queries");
		}

		@Override
		public int[] readInput() {
			return new int[] { n, 0, x };
		}

	}

	static final int K = 1500;

	static class Number implements Comparable<Number> {
		int val, pos, next;

		public Number(int val, int pos, int next) {
			this.val = val;
			this.pos = pos;
			this.next = next;
		}

		@Override
		public int compareTo(Number o) {
			return Integer.compare(val, o.val);
		}

	}

	void submit(Interactor it) {
		int[] tmp = it.readInput();
		int n = tmp[0];
		int start = tmp[1];
		int x = tmp[2];

		int[] left = new int[n];
		for (int i = 0; i < n; i++) {
			left[i] = i;
		}

		Number[] a = new Number[Math.min(K, n)];
		tmp = it.ask(start);
		if (tmp[0] >= x) {
			it.answer(tmp[0]);
			return;
		}
		a[0] = new Number(tmp[0], start, tmp[1]);

		left[start] = n - 1;

		for (int i = 1; i < a.length; i++) {

			int leftIdx = rng.nextInt(n - i);
			int idx = left[leftIdx];

			left[leftIdx] = left[n - i - 1];

			tmp = it.ask(idx);
			a[i] = new Number(tmp[0], idx, tmp[1]);
		}

		Arrays.sort(a);

		int begin = 0;
		while (begin + 1 < a.length && a[begin + 1].val < x) {
			begin++;
		}

		int until;
		if (begin == a.length - 1) {
			until = -1;
		} else {
			until = a[begin + 1].pos;
		}

		int cur = a[begin].next;
		while (cur != until) {
			tmp = it.ask(cur);
			if (tmp[0] >= x) {
				it.answer(tmp[0]);
				return;
			}
			cur = tmp[1];
		}

		if (until != -1) {
			it.answer(a[begin + 1].val);
		} else {
			it.answer(-1);
		}
	}

	void preCalc() {

	}

	void stress() {

	}

	void test() {
//		for (int i = 0; i < 10000; i++) {
//			submit(new LocalInteractor(50000));
//		}
		 submit(new LocalInteractor(50000));
	}

	B() throws IOException {
		br = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(System.out);
		// preCalc();
		submit(new SubmitInteractor());
		// stress();
//		test();
		out.close();
	}

	static final Random rng = new Random();

	static int rand(int l, int r) {
		return l + rng.nextInt(r - l + 1);
	}

	public static void main(String[] args) throws IOException {
		new B();
	}

	BufferedReader br;
	PrintWriter out;
	StringTokenizer st;

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

	String nextString() {
		try {
			return br.readLine();
		} catch (IOException e) {
			throw new RuntimeException(e);
		}
	}

	int nextInt() {
		return Integer.parseInt(nextToken());
	}

	long nextLong() {
		return Long.parseLong(nextToken());
	}

	double nextDouble() {
		return Double.parseDouble(nextToken());
	}
}