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>
#define rep(x,a,b) for(int x = a;x<=b;x++)
using namespace std;

inline int read()
{
	int x = 0;
	char c = getchar();
	while(c<'0'||c>'9') c = getchar();
	while(c>='0'&&c<='9') x = (x<<1) + (x<<3) + (c^48), c = getchar();
	return x;
}

const int MAXN = 2e5 + 1e4;
int a[MAXN];
bool is[MAXN];

struct pr
{
	int l,r;
}ans[MAXN];

int cnt;

void sp(int i,int j)
{
	swap(a[i],a[j]);
	a[i] = -a[i];
	a[j] = -a[j];
	ans[++cnt].l = i;
	ans[cnt].r = j;
}

void cp(int i,int j)
{
	sp(i,j);
	int cur = i;
	while(a[-a[cur]]>0) sp(cur,-a[cur]);
	cur = -a[cur];
	while(a[-a[cur]]>0) sp(cur,-a[cur]);
	sp(cur,-a[cur]);
}

int main()
{
	int n = read();
	rep(i,1,n) a[i] = read();
	int t = -1;
	rep(i,1,n)
	{
		if(is[i]) continue;
		if(a[i]==i) continue;
		int cur = i;
		do
		{
			is[cur] = 1;
			cur = a[cur];
		}
		while(cur!=i);
		if(t==-1) t = i;
		else
		{
			cp(t,i);
			t = -1;
		}
	}
	if(t!=-1)
	{
		bool tt = 0;
		rep(i,1,n)
		{
			if(a[i]==i)
			{
				tt = 1;
				cp(t,i);
				break;
			}
		}
		if(!tt)
		{
			int b = a[t];
			int c = a[b];
			sp(t,b);
			cp(b,c);
		}
	}
	cout<<cnt<<endl;
	for(int i = 1;i<=cnt;i++) cout<<ans[i].l<<" "<<ans[i].r<<endl;
	return 0;
}