Problem: You are given a permutation p of integers from 1 to n, where n is an even number. 

Your goal is to sort the permutation. To do so, you can perform zero or more operations of the following type: 

  * take two indices i and j such that 2 ⋅ |i - j| ≥ n and swap p_i and p_j. 



There is no need to minimize the number of operations, however you should use no more than 5 ⋅ n operations. One can show that it is always possible to do that.

Input

The first line contains a single integer n (2 ≤ n ≤ 3 ⋅ 10^5, n is even) — the length of the permutation. 

The second line contains n distinct integers p_1, p_2, …, p_n (1 ≤ p_i ≤ n) — the given permutation.

Output

On the first line print m (0 ≤ m ≤ 5 ⋅ n) — the number of swaps to perform.

Each of the following m lines should contain integers a_i, b_i (1 ≤ a_i, b_i ≤ n, |a_i - b_i| ≥ n/2) — the indices that should be swapped in the corresponding swap.

Note that there is no need to minimize the number of operations. We can show that an answer always exists.

Examples

Input


2
2 1


Output


1
1 2

Input


4
3 4 1 2


Output


4
1 4
1 4
1 3
2 4


Input


6
2 5 3 1 4 6


Output


3
1 5
2 5
1 4

Note

In the first example, when one swap elements on positions 1 and 2, the array becomes sorted.

In the second example, pay attention that there is no need to minimize number of swaps.

In the third example, after swapping elements on positions 1 and 5 the array becomes: [4, 5, 3, 1, 2, 6]. After swapping elements on positions 2 and 5 the array becomes [4, 2, 3, 1, 5, 6] and finally after swapping elements on positions 1 and 4 the array becomes sorted: [1, 2, 3, 4, 5, 6].

Solution (in JAVA):

Solution:
import javafx.scene.layout.Priority;
import java.io.*;
import java.lang.reflect.Array;
import java.net.Inet4Address;
import java.util.*;
import java.lang.*;
import java.util.HashMap;
import java.util.PriorityQueue;
public class templ implements Runnable{
    //static class pair implements Comparable
    static class pair
    {
        long f;
        long s;
        pair(long fi,long se)
        {
            f=fi;
            s=se;
        }
        /*public int compareTo(Object o)
        {
            pair pr=(pair)o;
            if(s>pr.s)
                return 1;
            if(s==pr.s)
            {
                if(f>pr.f)
                    return 1;
                else
                    return -1;
            }
            else
                return -1;
        }
        public boolean equals(Object o)
        {
            pair ob=(pair)o;
            int ff;
            int ss;
            if(o!=null)
            {
                ff=ob.f;
                ss=ob.s;
                if((ff==this.f)&&(ss==this.s))
                    return true;
            }
            return false;
        }
        public int hashCode()
        {
            return (this.f+" "+this.s).hashCode();
        }*/
    }
    public class triplet implements Comparable
    {
        int f,t;
        int s;
        triplet(int f,int s,int t)
        {
            this.f=f;
            this.s=s;
            this.t=t;
        }
        public boolean equals(Object o)
        {
            triplet ob=(triplet)o;
            int ff;
            int ss;
            int tt;
            if(o!=null)
            {
                ff=ob.f;
                ss=ob.s;
                tt=ob.t;
                if((ff==this.f)&&(ss==this.s)&&(tt==this.t))
                    return true;
            }
            return false;
        }
        public int hashCode()
        {
            return (this.f+" "+this.s+" "+this.t).hashCode();
        }
        public int compareTo(Object o)
        {
            triplet tr=(triplet)o;
            if(t>tr.t)
                return 1;
            else
                return -1;
        }
    }
    public int justlarge(long a[],int l,int r,long x)
    {
        int p=r+1;
        while(l<=r)
        {
            int mid=(l+r)/2;
            if(a[mid]<x)
            {
                l=mid+1;
            }
            else
            {
                p=mid;
                r = mid - 1;
            }
        }
        return p;
    }
    public static void main(String args[])throws Exception
    {
        new Thread(null,new templ(),"templ",1<<27).start();
    }
    public void run()
    {
        try
        {
            InputReader in = new InputReader(System.in);
            PrintWriter out = new PrintWriter(System.out);
            int n=in.ni();
            int a[]=new int[n+1];
            int b[]=new int[n+1];
            int c[]=new int[n+1];
            for(int i=1;i<=n;i++)
            {
                int x=in.ni();
                a[i]=x;
                b[x]=i;
                c[i]=x;
            }
            ArrayList<pair>al=new ArrayList<>();
            for(int i=1;i<=n;i++)
            {
                if(a[i]==i)
                    continue;
                int q=b[i];
                if(Math.abs(q-i)>=n/2)
                {
                    al.add(new pair(i,q));
                    int t=a[q];
                    a[q]=a[i];
                    a[i]=t;
                    b[a[q]]=q;
                    b[a[i]]=i;
                    continue;
                }
                if(q<=n/2)
                {
                    al.add(new pair(q,n));
                    al.add(new pair(i,n));
                    a[q]=a[n];
                    a[n]=a[i];
                    a[i]=i;
                    b[i]=i;
                    b[a[q]]=q;
                    b[a[n]]=n;
                }
                else
                {
                    if(i<=n/2)
                    {
                        al.add(new pair(1,q));
                        al.add(new pair(1,n));
                        al.add(new pair(i,n));
                        al.add(new pair(1,q));
                        a[q]=a[n];
                        a[n]=a[i];
                        a[i]=i;
                        b[i]=i;
                        b[a[q]]=q;
                        b[a[n]]=n;
                    }
                    else
                    {
                        al.add(new pair(1,q));
                        al.add(new pair(1,i));
                        al.add(new pair(1,q));
                        a[q]=a[i];
                        a[i]=i;
                        b[i]=i;
                        b[a[q]]=q;
                    }
                }
            }
            int ans=0;
            for(pair p : al)
            {
                if(p.f!=p.s)
                    ans++;
            }
            out.println(ans);
            for(pair p : al)
            {
                if(p.f!=p.s)
                {
                    int t=c[(int)p.f];
                    c[(int)p.f]=c[(int)p.s];
                    c[(int)p.s]=t;
                    out.println(p.f + " " + p.s);
                }
            }
            //for(int i=1;i<=n;i++)
            //    out.print(c[i]+" ");
            out.close();
        }
        catch(Exception e){
            return;
        }
    }
    static class InputReader {

        private final InputStream stream;
        private final byte[] buf = new byte[8192];
        private int curChar, snumChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int read() {
            if (snumChars == -1)
                throw new InputMismatchException();
            if (curChar >= snumChars) {
                curChar = 0;
                try {
                    snumChars = stream.read(buf);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (snumChars <= 0)
                    return -1;
            }
            return buf[curChar++];
        }

        public int ni() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public long nl() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
            do {
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }

        public int[] nextIntArray(int n) {
            int a[] = new int[n];
            for (int i = 0; i < n; i++) {
                a[i] = ni();
            }
            return a;
        }

        public String readString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }

        public String nextLine() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isEndOfLine(c));
            return res.toString();
        }

        public boolean isSpaceChar(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }

        private boolean isEndOfLine(int c) {
            return c == '\n' || c == '\r' || c == -1;
        }

    }
}