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 CPP):

Solution:
#pragma comment(linker, "/STACK:1000000000")
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <algorithm>
#include <memory.h>
#include <cassert>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <cmath>
#include <ctime>
#include <random>
#include <bitset>
#include <limits.h>
#include <fstream>
#include <list>
#include <numeric>

#define mp make_pair
#define all(a) (a).begin(), (a).end()
#define pll pair <ll, ll>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef long double ld;
#define uint unsigned int
#define mp make_pair

const int maxn = (int)2e5 + 10;
int v[maxn];
bool used[maxn];

int go(int p) {
	used[p] = true;
	int ans = 1;
	if (!used[v[p]]) {
		ans += go(v[p]);
	}
	return ans;
}

int tot[maxn];

mt19937 rr;

int main() {
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		scanf("%d", &v[i]);
		v[i]--;
		//v[i] = i;
	}

	//shuffle(v, v + n, rr);

	vector <pii> g;

	for (int i = 0; i < n; i++) {
		if (!used[i]) {
			g.push_back({ i, go(i) });
		}
	}

	sort(all(g), [&](pii a, pii b) {
		return a.second > b.second;
	});

	vector <pii> ans;

	if ((int)g.size() > 1) {
		for (int i = 0; i < (int)g.size(); i++) {
			if (g[i].second == 1) {
				break;
			}

			int a = g[i].first;
			int b = -1;
			
			if (i + 1 == (int)g.size()) {
				b = g[0].first;
			}
			else {
				b = g[i + 1].first;
				i++;
			}

			int x = v[a];

			swap(v[a], v[b]);
			ans.push_back({ a, b });
			tot[v[a]] ^= 1;
			tot[v[b]] ^= 1;

			while (v[v[a]] != x) {
				ans.push_back({ a, v[a] });
				tot[v[a]] ^= 1;
				tot[v[v[a]]] ^= 1;
				swap(v[a], v[v[a]]);
			}

			a = v[a];
			while (a != v[a]) {
				ans.push_back({ a, v[a] });
				tot[v[a]] ^= 1;
				tot[v[v[a]]] ^= 1;
				swap(v[a], v[v[a]]);
			}
		}
	}
	else {
		int a = g[0].first;
		ans.push_back({ a, v[a] });
		int x = v[a];
		tot[v[a]] ^= 1;
		tot[v[v[a]]] ^= 1;
		swap(v[a], v[v[a]]);
		ans.push_back({ x, v[a] });
		tot[v[x]] ^= 1;
		tot[v[v[a]]] ^= 1;
		swap(v[x], v[v[a]]);
		int s = 0;

		/*for (int i = 0; i < n; i++) {
			cout << v[i] << ' ';
		}

		for (int i = 0; i < n; i++) {
			cout << tot[i] << ' ';
		}

		exit(0);*/

		for (int i = 0; i < n; i++) {
			if (tot[v[i]] && !tot[v[v[i]]]) {
				s = i;
				break;
			}
		}

		while (!tot[v[v[s]]]) {
			ans.push_back({ s, v[s] });
			tot[v[s]] ^= 1;
			tot[v[v[s]]] ^= 1;
			swap(v[s], v[v[s]]);
		}

		s = v[s];

		while (s != v[s]) {
			ans.push_back({ s, v[s] });
			tot[v[s]] ^= 1;
			tot[v[v[s]]] ^= 1;
			swap(v[s], v[v[s]]);
		}
	}

	for (int i = 0; i < n; i++) {
		assert(tot[i] == 0);
	}

	for (int i = 0; i < n; i++) {
		assert(v[i] == i);
	}

	cout << (int)ans.size() << '\n';
	for (auto[x, y] : ans) {
		printf("%d %d\n", x + 1, y + 1);
	}
}