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 <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <cctype>
#include <cmath>
#include <vector>
#include <set>
#include <bitset>
#include <map>
#include <stack>
#include <queue>
#include <ctime>
#define _for(i,a,b) for(int i=(a);i<(b);++i)
#define _rep(i,a,b) for(int i=(a);i<=(b);++i)
#define mem(a,b) memset(a,b,sizeof(a))
using namespace std;
typedef long long LL;
inline int read_int(){
	int t=0;bool sign=false;char c=getchar();
	while(!isdigit(c)){sign|=c=='-';c=getchar();}
	while(isdigit(c)){t=(t<<1)+(t<<3)+(c&15);c=getchar();}
	return sign?-t:t;
}
inline LL read_LL(){
	LL t=0;bool sign=false;char c=getchar();
	while(!isdigit(c)){sign|=c=='-';c=getchar();}
	while(isdigit(c)){t=(t<<1)+(t<<3)+(c&15);c=getchar();}
	return sign?-t:t;
}
inline char get_char(){
	char c=getchar();
	while(c==' '||c=='\n'||c=='\r')c=getchar();
	return c;
}
inline void write(LL x){
	char c[21],len=0;
	if(!x)return putchar('0'),void();
	if(x<0)x=-x,putchar('-');
	while(x)c[++len]=x%10,x/=10;
	while(len)putchar(c[len--]+48);
}
inline void space(LL x){write(x),putchar(' ');}
inline void enter(LL x){write(x),putchar('\n');}
const int MAXN=2e5+5;
int a[MAXN];
bool vis[MAXN];
vector<pair<int,int> > ans;
void Swap(int p1,int p2){
	swap(a[p1],a[p2]);
	ans.push_back(make_pair(p1,p2));
}
void solve(int u,int v){
	while(a[u]!=v)Swap(u,a[u]);
	while(a[v]!=u)Swap(v,a[v]);
	Swap(u,v);
}
int main()
{
//	freopen("test.in","r",stdin);
//	freopen("test.out","w",stdout);
	int n=read_int(),last=0;
	_rep(i,1,n)a[i]=read_int();
	_rep(i,1,n){
		if(vis[i])continue;
		vis[i]=true;
		if(a[i]==i)continue;
		int pos=i;
		while(a[pos]!=i){
			pos=a[pos];
			vis[pos]=true;
		}
		if(last==0)
		last=i;
		else{
			Swap(i,last);
			solve(i,last);
			last=0;
		}
	}
	if(last){
		bool flag=false;
		_rep(i,1,n){
			if(a[i]==i){
				Swap(i,last);
				solve(i,last);
				flag=true;
				break;
			}
		}
		if(!flag){
			int p1=last,p2=a[p1],p3=a[p2];
			Swap(p1,p2);
			Swap(p2,p3);
			solve(p1,p2);
		}
	}
	enter(ans.size());
	_for(i,0,ans.size())
	printf("%d %d\n",ans[i].first,ans[i].second);
	return 0;
}