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;
static int LOCAL = 0;
const long long int mod = 1000000007ll;
const long long int MOD = 1000000009ll;
const long long int INF = LLONG_MAX / 10;
const int inf = INT_MAX / 10;
long long int count_bit(long long int _x) {
  long long int _ret = 0;
  while (_x) {
    if (_x % 2 == 1) _ret++;
    _x /= 2;
  }
  return _ret;
}
bool check_bit(long long int _mask, long long int _i) {
  long long int x = 1;
  return (_mask & (x << _i)) == 0 ? false : true;
}
long long int set_bit(long long int _mask, long long int _i) {
  long long int x = 1;
  _mask = _mask | (x << _i);
  return _mask;
}
long long int msb(long long int _mask) {
  long long int ret = -1;
  int cnt = 0;
  while (_mask) {
    if (_mask & 1) ret = cnt;
    _mask /= 2;
    cnt++;
  }
  return ret;
}
long long int powermod(long long int _a, long long int _b,
                       long long int _m = mod) {
  long long int _r = 1;
  while (_b) {
    if (_b % 2 == 1) _r = (_r * _a) % _m;
    _b /= 2;
    _a = (_a * _a) % _m;
  }
  return _r;
}
long long int power(long long int _a, long long int _b) {
  long long int _r = 1;
  while (_b) {
    if (_b % 2 == 1) _r = (_r * _a);
    _b /= 2;
    _a = (_a * _a);
  }
  return _r;
}
long long int add(long long int a, long long int b, long long int m = mod) {
  long long int x = a + b;
  while (x >= m) x -= m;
  return x;
}
long long int sub(long long int a, long long int b, long long int m = mod) {
  long long int x = a - b;
  while (x < 0) x += m;
  return x;
}
long long int mul(long long int a, long long int b, long long int m = mod) {
  return ((a % m) * (b % m)) % m;
}
long long int gcd(long long int a, long long int b) {
  while (a && b) a > b ? a %= b : b %= a;
  return a + b;
}
long long int lcm(long long int a, long long int b) {
  return (max(a, b) / gcd(a, b)) * min(a, b);
}
struct pair_hash {
  std::size_t operator()(
      const std::pair<long long int, long long int> &p) const {
    auto h1 = std::hash<long long int>{}(p.first);
    auto h2 = std::hash<long long int>{}(p.second);
    return h1 ^ h2;
  }
};
struct cmp {
  bool operator()(pair<int, int> const &l, pair<int, int> const &r) {
    return l.first > r.first;
  }
} myobject;
const int N = 300010;
int n, a[N], pos[N];
vector<pair<int, int> > v;
void noname(int i, int j) {
  v.push_back({i, j});
  swap(pos[a[i]], pos[a[j]]);
  swap(a[i], a[j]);
}
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    pos[a[i]] = i;
  }
  for (int i = 1; i <= n; i++) {
    if (pos[i] == i) continue;
    if (2 * abs(pos[i] - i) >= n)
      noname(i, pos[i]);
    else {
      if (2 * abs(pos[i] - n) >= n) {
        noname(pos[i], n);
        noname(i, n);
      } else {
        noname(pos[i], pos[1]);
        if (2 * abs(i - 1) >= n) {
          noname(pos[i], i);
          noname(pos[1], 1);
        } else {
          noname(pos[i], n);
          noname(pos[i], i);
          noname(pos[1], 1);
        }
      }
    }
  }
  printf("%d", (int)v.size());
  printf("\n");
  for (auto p : v) printf("%d %d", p.first, p.second), printf("\n");
  return 0;
}