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 <bits/stdc++.h>

#define isNum(a) (a >= '0' && a <= '9')
#define SP putchar(' ')
#define EL putchar('\n')
#define File(a) freopen(a ".in", "r", stdin), freopen(a ".out", "w", stdout)

template <typename T>
void read(T &);
template <typename T>
void write(const T &);

typedef unsigned uint;
typedef long long ll;
typedef unsigned long long ull;
typedef std::pair<int, int> pii;
const int iinf = 2147483647;
const ll llinf = 9223372036854775807ll;

const int N = 200005;

void swap(int u, int v);
void single(std::vector<int> &P);
void merge(std::vector<int> &P1, std::vector<int> &P2);

std::vector<std::vector<int> > A;
std::vector<pii> Ans;
bool vis[N];
int p[N];
int n;

int main() {
  read(n);
  for (int i = 1; i <= n; ++i) {
    read(p[i]);
  }
  for (int i = 1; i <= n; ++i) {
    if (!vis[i]) {
      std::vector<int> tmp;
      for (int j = i; !vis[j]; j = p[j]) {
        tmp.push_back(j);
        vis[j] = true;
      }
      A.push_back(tmp);
    }
  }
  if (A.size() == 1) {
    single(A.front());
  } else {
    if (A.size() & 1) {
      A.push_back(std::vector<int>{A[0][0]});
    }
    for (int i = 0; i < static_cast<int>(A.size()); i += 2) {
      merge(A[i], A[i + 1]);
    }
  }
  write(Ans.size()), EL;
  for (auto [u, v] : Ans) write(u), SP, write(v), EL;
  return 0;
}

void swap(int u, int v) { Ans.emplace_back(u, v); }
void single(std::vector<int> &P) {
  for (int i = 1; i < static_cast<int>(P.size()) - 1; ++i) {
    swap(P[0], P[i]);
  }
  swap(P[1], P.back());
  swap(P[0], P.back());
  swap(P[0], P[1]);
}
void merge(std::vector<int> &P1, std::vector<int> &P2) {
  swap(P1[0], P2[0]);
  for (int i = 1; i < static_cast<int>(P1.size()); ++i) {
    swap(P1[i], P2[0]);
  }
  for (int i = 1; i < static_cast<int>(P2.size()); ++i) {
    swap(P2[i], P1[0]);
  }
  swap(P1[0], P2[0]);
}

template <typename T>
void read(T &Re) {
  T k = 0;
  char ch = getchar();
  int flag = 1;
  while (!isNum(ch)) {
    if (ch == '-') flag = -1;
    ch = getchar();
  }
  while (isNum(ch)) {
    k = (k << 1) + (k << 3) + ch - '0';
    ch = getchar();
  }
  Re = flag * k;
}
template <typename T>
void write(const T &Wr) {
  if (Wr < 0) {
    putchar('-');
    write(-Wr);
  } else {
    if (Wr < 10) {
      putchar(Wr + '0');
    } else {
      write(Wr / 10);
      putchar((Wr % 10) + '0');
    }
  }
}