Problem: There are n coins labeled from 1 to n. Initially, coin c_i is on position i and is facing upwards ((c_1, c_2, ..., c_n) is a permutation of numbers from 1 to n). You can do some operations on these coins. 

In one operation, you can do the following:

  * Choose 2 distinct indices i and j.

  * Then, swap the coins on positions i and j.

  * Then, flip both coins on positions i and j. (If they are initially faced up, they will be faced down after the operation and vice versa)




Construct a sequence of at most n+1 operations such that after performing all these operations the coin i will be on position i at the end, facing up.

Note that you do not need to minimize the number of operations.

Input

The first line contains an integer n (3 ≤ n ≤ 2 ⋅ 10^5) — the number of coins.

The second line contains n integers c_1,c_2,...,c_n (1 ≤ c_i ≤ n, c_i ≠ c_j for i≠ j).

Output

In the first line, output an integer q (0 ≤ q ≤ n+1) — the number of operations you used.

In the following q lines, output two integers i and j (1 ≤ i, j ≤ n, i ≠ j) — the positions you chose for the current operation.

Examples

Input


3
2 1 3


Output


3
1 3
3 2
3 1


Input


5
1 2 3 4 5


Output


0

Note

Let coin i facing upwards be denoted as i and coin i facing downwards be denoted as -i.

The series of moves performed in the first sample changes the coins as such:

  * [~~~2,~~~1,~~~3] 
  * [-3,~~~1,-2] 
  * [-3,~~~2,-1] 
  * [~~~1,~~~2,~~~3] 



In the second sample, the coins are already in their correct positions so there is no need to swap.

Solution (in JAVA):

Solution:
import static java.lang.Integer.parseInt;
import static java.lang.Long.parseLong;
import static java.lang.System.exit;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class G {

	static void solve() throws Exception {
		int n = scanInt(), p[] = new int[n];
		for (int i = 0; i < n; i++) {
			p[i] = scanInt() - 1;
		}
		int cycle[] = new int[n];
		int cyclePos[] = new int[n + 1];
		int cycleCnt = 0;
		boolean have[] = new boolean[n];
		for (int i = 0; i < n; i++) {
			if (have[i]) {
				continue;
			}
			int pos = cyclePos[cycleCnt];
			for (int j = i; !have[j]; j = p[j]) {
				have[j] = true;
				cycle[pos++] = j;
			}
			cyclePos[++cycleCnt] = pos;
		}
		if (cycleCnt == 1) {
			out.println(n + 1);
			out.println((cycle[0] + 1) + " " + (cycle[1] + 1));
			out.println((cycle[1] + 1) + " " + (cycle[2] + 1));
			out.println((cycle[0] + 1) + " " + (cycle[2] + 1));
			for (int i = 3; i < n; i++) {
				out.println((cycle[1] + 1) + " " + (cycle[i] + 1));
			}
			out.println((cycle[0] + 1) + " " + (cycle[1] + 1));
		} else {
			out.println(n + cycleCnt % 2);
			if (cycleCnt % 2 != 0) {
				out.println((cycle[cyclePos[1]] + 1) + " " + (cycle[cyclePos[2]] + 1));
				out.println((cycle[cyclePos[0]] + 1) + " " + (cycle[cyclePos[1]] + 1));
				for (int j = cyclePos[0] + 1; j < cyclePos[1]; j++) {
					out.println((cycle[cyclePos[1]] + 1) + " " + (cycle[j] + 1));
				}
				out.println((cycle[cyclePos[0]] + 1) + " " + (cycle[cyclePos[1]] + 1));
			}
			for (int i = cycleCnt % 2; i < cycleCnt; i += 2) {
				if (i != 1) {
					out.println((cycle[cyclePos[i]] + 1) + " " + (cycle[cyclePos[i + 1]] + 1));
				}
				for (int j = cyclePos[i + 1] + 1; j < cyclePos[i + 2]; j++) {
					out.println((cycle[cyclePos[i]] + 1) + " " + (cycle[j] + 1));
				}
				for (int j = cyclePos[i] + 1; j < cyclePos[i + 1]; j++) {
					out.println((cycle[cyclePos[i + 1]] + 1) + " " + (cycle[j] + 1));
				}
				out.println((cycle[cyclePos[i]] + 1) + " " + (cycle[cyclePos[i + 1]] + 1));
			}
		}
	}

	static int scanInt() throws IOException {
		return parseInt(scanString());
	}

	static long scanLong() throws IOException {
		return parseLong(scanString());
	}

	static String scanString() throws IOException {
		while (tok == null || !tok.hasMoreTokens()) {
			tok = new StringTokenizer(in.readLine());
		}
		return tok.nextToken();
	}

	static BufferedReader in;
	static PrintWriter out;
	static StringTokenizer tok;

	public static void main(String[] args) {
		try {
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(System.out);
			solve();
			in.close();
			out.close();
		} catch (Throwable e) {
			e.printStackTrace();
			exit(1);
		}
	}
}