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:

#include <bits/stdc++.h>

const int maxn = 1e6 + 22;

int vis[maxn],n,p[maxn],q[maxn],mark[maxn],cyc[maxn],tl;
std::vector<std::pair<int,int> >answ; 

void swap(int x,int y) {
	std::swap(p[x],p[y]);
	q[p[x]] = x;
	q[p[y]] = y;
	vis[p[x]] ^= 1;
	vis[p[y]] ^= 1;
	answ.push_back({x,y}); 
}

void work(int x,int y) {
	assert(vis[x] == 1 && vis[y] == 1);
	while (p[y] != x) { int u = p[y]; swap(y,q[y]); y = u; }
	while (p[x] != y) { int u = p[x]; swap(x,q[x]); x = u; }
	swap(x,y);
}

void solve_big_cycle() {
	int u = 1; int v = q[1]; int w = p[1]; int z = p[w];
	swap(u,v); swap(u,w);
	work(w,z);
}

void solve(int x,int y) {
	int u = p[x], v = p[y];
	swap(x,y);
	work(u,v);
}	

int main() {
	srand(time(0));
	scanf("%d",&n);
//	for (int i = 1; i <= n; ++ i) p[i] = i;
//	std::random_shuffle(p+1,p+n+1);
//	for (int i = 1; i <= n; ++ i) printf("%d ",p[i]); puts("");
	for (int i = 1; i <= n; ++ i) {
		scanf("%d",&p[i]);
		q[p[i]] = i;
	}
	for (int i = 1; i <= n; ++ i) {
		if (!mark[i]) {
			cyc[++tl] = i;;
			int u = i; 
			while (!mark[u]) { 
				mark[u] = tl; 
				u = p[u];
			}
		}
	} if (tl == 1) solve_big_cycle();
	else for (int i = 1; i <= tl; i += 2) solve(cyc[i],cyc[i%tl+1]); 
	printf("%d\n",answ.size());
	for (auto p:answ) { printf("%d %d\n",p.first,p.second); }
//	for (int i = 1; i <= n; ++ i) printf("%d ",p[i]); puts("");
//	for (int i = 1; i <= n; ++ i) printf("%d ",vis[i]); puts("");
	return 0;
}