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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
vector<long long> val;
long long max(long long a, long long b) {
  if (a >= b)
    return a;
  else
    return b;
}
long long min(long long a, long long b) {
  if (a >= b)
    return b;
  else
    return a;
}
long long checkprime(long long a) {
  long long flag = 1;
  for (long long i = 2; i <= sqrt(a); i++) {
    if (a % i == 0) {
      flag = 0;
      break;
    }
  }
  return flag;
}
unsigned long long power(unsigned long long x, long long y, long long p) {
  unsigned long long res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
unsigned long long modInverse(unsigned long long n, long long p) {
  return power(n, p - 2, p);
}
unsigned long long nCrModPFermat(unsigned long long n, long long r,
                                 long long p) {
  if (n < r) return 0;
  if (r == 0) return 1;
  unsigned long long fac[n + 1];
  fac[0] = 1;
  for (long long i = 1; i <= n; i++) fac[i] = (fac[i - 1] * i) % p;
  return (fac[n] * modInverse(fac[r], p) % p * modInverse(fac[n - r], p) % p) %
         p;
}
long long factorial(long long n, long long p) {
  long long res = 1, i;
  for (i = 2; i <= n; i++) res = (long long)(res * i) % p;
  return res;
}
bitset<100000> b;
vector<long long> primes;
void Sieve() {
  b.set();
  b[0] = 0;
  b[1] = 0;
  for (long long i = 2; i < 100000; i++) {
    if (b[i]) {
      primes.push_back(i);
      for (long long j = i * i; j < 100000; j += i) {
        b[j] = 0;
      }
    }
  }
}
void sw(long long *a, long long *pos, long long num, long long dest_pos,
        vector<pair<long long, long long>> &v) {
  v.push_back(make_pair(dest_pos, pos[num]));
  long long temp = pos[num];
  pos[a[dest_pos - 1]] = temp;
  swap(a[dest_pos - 1], a[pos[num] - 1]);
  pos[num] = dest_pos;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n;
  cin >> n;
  long long a[n];
  long long pos[n + 1];
  pos[0] = 0;
  vector<pair<long long, long long>> v;
  long long og[n];
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
    og[i] = a[i];
    pos[a[i]] = i + 1;
  }
  long long num = 1;
  while (num < n) {
    if (pos[num] == num) num++;
    if (pos[num] - num >= n / 2) {
      v.push_back(make_pair(num, pos[num]));
      long long tmp = pos[num];
      pos[a[num - 1]] = tmp;
      swap(a[num - 1], a[pos[num] - 1]);
      pos[num] = num;
    } else {
      long long val1 = abs(1 - pos[num]);
      long long val2 = abs(n - pos[num]);
      if (val1 >= n / 2) {
        v.push_back(make_pair(1, pos[num]));
        long long tmp = pos[num];
        pos[a[0]] = tmp;
        swap(a[0], a[pos[num] - 1]);
        pos[num] = 1;
        if (abs(num - pos[num]) >= n / 2) {
          sw(a, pos, num, num, v);
        } else {
          sw(a, pos, num, n, v);
          sw(a, pos, num, num, v);
        }
      } else {
        sw(a, pos, num, n, v);
        if (abs(num - pos[num]) >= n / 2) {
          sw(a, pos, num, num, v);
        } else {
          sw(a, pos, num, 1, v);
          sw(a, pos, num, num, v);
        }
      }
    }
    num++;
  }
  if (a[0] != 1 && a[n - 1] != n) {
    v.push_back(make_pair(1, n));
  }
  cout << v.size() << endl;
  for (long long i = 0; i < v.size(); i++) {
    cout << v[i].first << " " << v[i].second << endl;
  }
}