Problem: This is an interactive problem.

Little Dormi was faced with an awkward problem at the carnival: he has to guess the edges of an unweighted tree of n nodes! The nodes of the tree are numbered from 1 to n.

The game master only allows him to ask one type of question:

  * Little Dormi picks a node r (1 ≤ r ≤ n), and the game master will reply with an array d_1, d_2, …, d_n, where d_i is the length of the shortest path from node r to i, for all 1 ≤ i ≤ n.



Additionally, to make the game unfair challenge Little Dormi the game master will allow at most ⌈n/2⌉ questions, where ⌈ x ⌉ denotes the smallest integer greater than or equal to x.

Faced with the stomach-churning possibility of not being able to guess the tree, Little Dormi needs your help to devise a winning strategy!

Note that the game master creates the tree before the game starts, and does not change it during the game.

Input

The first line of input contains the integer n (2 ≤ n ≤ 2 000), the number of nodes in the tree.

You will then begin interaction.

Output

When your program has found the tree, first output a line consisting of a single "!" followed by n-1 lines each with two space separated integers a and b, denoting an edge connecting nodes a and b (1 ≤ a, b ≤ n). Once you are done, terminate your program normally immediately after flushing the output stream.

You may output the edges in any order and an edge (a,b) is considered the same as an edge (b,a). Answering is not considered as a query.

Interaction

After taking input, you may make at most ⌈n/2⌉ queries. Each query is made in the format "? r", where r is an integer 1 ≤ r ≤ n that denotes the node you want to pick for that query.

You will then receive n space separated integers d_1, d_2, …, d_n, where d_i is the length of the shortest path from node r to i, followed by a newline.

After printing a query do not forget to output end of line and flush the output. Otherwise, you will get Idleness limit exceeded. To do this, use:

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



If at any point you make an invalid query or try to make more than ⌈ n/2 ⌉ queries, the interaction will terminate immediately and you will receive a Wrong Answer verdict.

Hacks

To hack a solution, use the following format.

The first line contains the integer n (2 ≤ n ≤ 2 000).

The next n−1 lines contain two integers u and v (1 ≤ u,v ≤ n) denoting an edge between u and v (u ≠ v). These n-1 edges must form a tree.

Examples

Input


4

0 1 2 2

1 0 1 1

Output


? 1

? 2

!
4 2
1 2
2 3


Input


5

2 2 1 1 0


Output


? 5

!
4 5
3 5
2 4
1 3

Note

Here is the tree from the first example.

<image>

Notice that the edges can be output in any order.

Additionally, here are the answers for querying every single node in example 1:

  * 1: [0,1,2,2] 
  * 2: [1,0,1,1] 
  * 3: [2,1,0,2] 
  * 4: [2,1,2,0]



Below is the tree from the second example interaction.

<image>

Lastly, here are the answers for querying every single node in example 2:

  * 1: [0,4,1,3,2] 
  * 2: [4,0,3,1,2] 
  * 3: [1,3,0,2,1] 
  * 4: [3,1,2,0,1] 
  * 5: [2,2,1,1,0]

Solution (in JAVA):

Solution:
import java.awt.Point;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.TreeSet;

public class Main {

	public static void main(String[] args) {
		new Main();
	}

	public Main() {
		FastScanner fs = new FastScanner();
		java.io.PrintWriter out = new java.io.PrintWriter(System.out);
		solve(fs, out);
		out.flush();
	}

	public void solve(FastScanner fs, java.io.PrintWriter out) {
		int n = fs.nextInt();
		out.println("? 1");
		out.flush();
		TreeSet<Integer> set = new TreeSet<>();
		HashSet<Point> list = new HashSet<>();
		{
			ArrayList<Integer> odd = new ArrayList<>(), even = new ArrayList<>();
			for (int i = 1;i <= n;++ i) {
				int d = fs.nextInt();
				if (d == 1) list.add(new Point(1, i));
				if (i == 1) continue;
				if (d % 2 == 0) even.add(i);
				else odd.add(i);
			}
			if (odd.size() < even.size()) set.addAll(odd);
			else set.addAll(even);
		}

		while(!set.isEmpty()) {
			int tmp = set.pollFirst();
			out.println("? " + tmp);
			out.flush();
			for (int i = 1;i <= n;++ i) {
				if (fs.nextInt() == 1) {
					list.add(new Point(Math.min(tmp, i), Math.max(tmp, i)));
					set.remove(i);
				}
			}
		}
		out.println("!");
		for (Point p : list) out.println(p.x + " " + p.y);
	}
}

class FastScanner {

	private final java.io.InputStream in = System.in;
	private final byte[] buffer = new byte[8192];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) return true;
		ptr = 0;
		try {
			buflen = in.read(buffer);
		} catch (java.io.IOException e) {
			e.printStackTrace();
		}
		return buflen > 0;
	}

	private byte readByte() {
		return hasNextByte() ? buffer[ptr++ ] : -1;
	}

	private static boolean isPrintableChar(byte c) {
		return 32 < c || c < 0;
	}

	private static boolean isNumber(int c) {
		return '0' <= c && c <= '9';
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++ ;
		return hasNextByte();
	}

	public String next() {
		if (!hasNext()) throw new java.util.NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		byte b;
		while (isPrintableChar(b = readByte()))
			sb.appendCodePoint(b);
		return sb.toString();
	}

	public final char nextChar() {
		if (!hasNext()) throw new java.util.NoSuchElementException();
		return (char)readByte();
	}

	public final long nextLong() {
		if (!hasNext()) throw new java.util.NoSuchElementException();
		long n = 0;
		try {
			byte b = readByte();
			if (b == '-') {
				while (isNumber(b = readByte()))
					n = n * 10 + '0' - b;
				return n;
			} else if (!isNumber(b)) throw new NumberFormatException();
			do
				n = n * 10 + b - '0';
			while (isNumber(b = readByte()));
		} catch (java.util.NoSuchElementException e) {}
		return n;
	}

	public final int nextInt() {
		if (!hasNext()) throw new java.util.NoSuchElementException();
		int n = 0;
		try {
			byte b = readByte();
			if (b == '-') {
				while (isNumber(b = readByte()))
					n = n * 10 + '0' - b;
				return n;
			} else if (!isNumber(b)) throw new NumberFormatException();
			do
				n = n * 10 + b - '0';
			while (isNumber(b = readByte()));
		} catch (java.util.NoSuchElementException e) {}
		return n;
	}

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

class Arrays {

	public static void sort(final int[] array) {
		sort(array, 0, array.length);
	}

	public static void sort(final int[] array, int fromIndex, int toIndex) {
		if (toIndex - fromIndex  <= 512) {
			java.util.Arrays.sort(array, fromIndex, toIndex);
			return;
		}
		sort(array, fromIndex, toIndex, 0, new int[array.length]);
	}

	private static final void sort(int[] a, final int from, final int to, final int l, final int[] bucket) {
		if (to - from  <= 512) {
			java.util.Arrays.sort(a, from, to);
			return;
		}
		final int BUCKET_SIZE = 256;
		final int INT_RECURSION = 4;
		final int MASK = 0xff;
		final int shift = l << 3;
		final int[] cnt = new int[BUCKET_SIZE + 1];
		final int[] put = new int[BUCKET_SIZE];
		for (int i = from; i < to; i++) ++ cnt[(a[i] >>> shift & MASK) + 1];
		for (int i = 0; i < BUCKET_SIZE; i++) cnt[i + 1] += cnt[i];
		for (int i = from; i < to; i++) {
			int bi = a[i] >>> shift & MASK;
			bucket[cnt[bi] + put[bi]++] = a[i];
		}
		for (int i = BUCKET_SIZE - 1, idx = from; i >= 0; i--) {
			int begin = cnt[i];
			int len = cnt[i + 1] - begin;
			System.arraycopy(bucket, begin, a, idx, len);
			idx += len;
	    }
		final int nxtL = l + 1;
		if (nxtL < INT_RECURSION) {
			sort(a, from, to, nxtL, bucket);
			if (l == 0) {
				int lft, rgt;
				lft = from - 1; rgt = to;
				while (rgt - lft > 1) {
					int mid = lft + rgt >> 1;
					if (a[mid] < 0) lft = mid;
					else rgt = mid;
				}
				reverse(a, from, rgt);
				reverse(a, rgt, to);
	        }
	    }
	}

	public static void sort(final long[] array) {
		sort(array, 0, array.length);
	}

	public static void sort(final long[] array, int fromIndex, int toIndex) {
		if (toIndex - fromIndex  <= 512) {
			java.util.Arrays.sort(array, fromIndex, toIndex);
			return;
		}
		sort(array, fromIndex, toIndex, 0, new long[array.length]);
	}

	private static final void sort(long[] a, final int from, final int to, final int l, final long[] bucket) {
		final int BUCKET_SIZE = 256;
		final int LONG_RECURSION = 8;
		final int MASK = 0xff;
		final int shift = l << 3;
		final int[] cnt = new int[BUCKET_SIZE + 1];
		final int[] put = new int[BUCKET_SIZE];
		for (int i = from; i < to; i++) ++ cnt[(int) ((a[i] >>> shift & MASK) + 1)];
		for (int i = 0; i < BUCKET_SIZE; i++) cnt[i + 1] += cnt[i];
		for (int i = from; i < to; i++) {
			int bi = (int) (a[i] >>> shift & MASK);
			bucket[cnt[bi] + put[bi]++] = a[i];
		}
		for (int i = BUCKET_SIZE - 1, idx = from; i >= 0; i--) {
			int begin = cnt[i];
			int len = cnt[i + 1] - begin;
			System.arraycopy(bucket, begin, a, idx, len);
			idx += len;
	    }
		final int nxtL = l + 1;
		if (nxtL < LONG_RECURSION) {
			sort(a, from, to, nxtL, bucket);
			if (l == 0) {
				int lft, rgt;
				lft = from - 1; rgt = to;
				while (rgt - lft > 1) {
					int mid = lft + rgt >> 1;
					if (a[mid] < 0) lft = mid;
					else rgt = mid;
				}
				reverse(a, from, rgt);
				reverse(a, rgt, to);
	        }
	    }
	}

	public static void reverse(int[] array) {
		reverse(array, 0, array.length);
	}

	public static void reverse(int[] array, int fromIndex, int toIndex) {
		for (-- toIndex;fromIndex < toIndex;++ fromIndex, -- toIndex) {
			int swap = array[fromIndex];
			array[fromIndex] = array[toIndex];
			array[toIndex] = swap;
		}
	}

	public static void reverse(long[] array) {
		reverse(array, 0, array.length);
	}

	public static void reverse(long[] array, int fromIndex, int toIndex) {
		for (-- toIndex;fromIndex < toIndex;++ fromIndex, -- toIndex) {
			long swap = array[fromIndex];
			array[fromIndex] = array[toIndex];
			array[toIndex] = swap;
		}
	}
}

class IntMath {

	public static int gcd(int a, int b) {
		while (a != 0)
			if ((b %= a) != 0) a %= b;
			else return a;
		return b;
	}

	public static int gcd(int... array) {
		int ret = array[0];
		for (int i = 1; i < array.length; ++i)
			ret = gcd(ret, array[i]);
		return ret;
	}

	public static long gcd(long a, long b) {
		while (a != 0)
			if ((b %= a) != 0) a %= b;
			else return a;
		return b;
	}

	public static long gcd(long... array) {
		long ret = array[0];
		for (int i = 1; i < array.length; ++i)
			ret = gcd(ret, array[i]);
		return ret;
	}

	public static long lcm(long a, long b) {
		return a / gcd(a, b) * b;
	}

	public static int pow(int a, int b) {
		int ans = 1;
		for (int mul = a; b > 0; b >>= 1, mul *= mul)
			if ((b & 1) != 0) ans *= mul;
		return ans;
	}

	public static long pow(long a, long b) {
		long ans = 1;
		for (long mul = a; b > 0; b >>= 1, mul *= mul)
			if ((b & 1) != 0) ans *= mul;
		return ans;
	}

	public static int pow(int a, long b, int mod) {
		if (b < 0) b = b % (mod - 1) + mod - 1;
		long ans = 1;
		for (long mul = a; b > 0; b >>= 1, mul = mul * mul % mod)
			if ((b & 1) != 0) ans = ans * mul % mod;
		return (int)ans;
	}

	public static int pow(long a, long b, int mod) {
		return pow((int)(a % mod), b, mod);
	}

	public static int floorsqrt(long n) {
		return (int)Math.sqrt(n + 0.1);
	}

	public static int ceilsqrt(long n) {
		return n <= 1 ? (int)n : (int)Math.sqrt(n - 0.1) + 1;
	}
}