#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define debug(x) cout<<#x<<':'<<x<<endl
const int N = 2e5+20;
int cnt,f[N],a[N],col[N],vis[N];
int n,pos[N],tmp1,tmp2,tmp3;
vector<int> cir[N];
vector<pair<int,int> > ans;
void solve(int i,int j)
{
	ans.push_back(make_pair(i,j));
}
int main()
{
	scanf("%d",&n);
	for(int i=1,x;i<=n;i++)
		scanf("%d",&x),pos[i]=x;
	cnt = 0;
	for(int i=1;i<=n;i++)if(!vis[i])
	{
		vis[i] = 1;++cnt;
		cir[cnt].push_back(i);
		for(int j=pos[i];j!=i;j=pos[j])
			vis[j]=1,cir[cnt].push_back(j);
	}
	for(int i=1;i<=cnt;i+=2)
	{
		if(i+1>cnt)break;
		solve(cir[i][0],cir[i+1][0]);
		for(int j=1;j<cir[i].size();j++)
			solve(cir[i][j],cir[i+1][0]);
		for(int j=1;j<cir[i+1].size();j++)
			solve(cir[i+1][j],cir[i][0]);
		solve(cir[i][0],cir[i+1][0]);
	}
	if(cnt%2)
	{
		if(cir[cnt].size()==2)
		{
			int k = 1;
			while(k==cir[cnt][0]||k==cir[cnt][1])k++;
			solve(cir[cnt][0],k);solve(cir[cnt][1],k);solve(cir[cnt][0],k);
		}
		else if(cir[cnt].size()!=1)
		{
			for(int i=1;i<cir[cnt].size()-1;i++)solve(cir[cnt][0],cir[cnt][i]);
			solve(cir[cnt][1],cir[cnt].back());
			solve(cir[cnt][0],cir[cnt].back());
			solve(cir[cnt][0],cir[cnt][1]);
		}
	}
	printf("%d\n",ans.size());
	for(auto x:ans)
		printf("%d %d\n",x.first,x.second);
	return 0;
}
