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 <ext/pb_ds/assoc_container.hpp>
 #include <ext/pb_ds/priority_queue.hpp>

 using namespace __gnu_pbds;


__gnu_pbds::priority_queue<int, less<int>> pq;
gp_hash_table<int, int> mp;
*/

/** Begin fast allocation */
/*
const int mx_MEM = 10 * 1e7;
int mpos = 0;
char mem[mx_MEM];

inline void *operator new(size_t n) {
    assert((mpos += n) <= mx_MEM);
    return (void *) (mem + mpos - n);
}

inline void operator delete(void *) noexcept {} // must have!
*/
/** End fast allocation */

/** Pragmas */
// mt19937 gen(2281337);

//#pragma GCC optimize("O3", "Ofast", "unroll-loops", "unswitch-loops", "fast-math", "no-stack-protector")

//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,abm,mmx,avx")
// sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,abm,mmx,
//#pragma comment(linker, "/STACK:66777216")

/*
 * @author kamil.sharipov
 */

#include <bits/stdc++.h>

//#define int long long
#define all(x) (x).begin(), (x).end()
#define fo(i, a, b) for (int i = a; i < b; ++i)
#define ll long long
#define pii pair<int, int>

using namespace std;

int n;
vector<int> a, was;
vector<vector<int> > circ;

vector<pii > ans;

signed main() {
#ifdef _LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin >> n;
    a.resize(n), circ.resize(n), was.resize(n);

    int cnt = 0;
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
        a[i]--;
    }

    for (int i = 0; i < n; ++i) {
        if (was[i] == 0) {
            was[i] = 1;

            if (a[i] != i) {
                circ[cnt].push_back(i);
                int cur = a[i];
                while (cur != i) {
                    circ[cnt].push_back(cur);
                    was[cur] = 1;
                    cur = a[cur];
                }
                cnt++;
            }
        }
    }

    for (int i = 0; i + 1 < cnt; i += 2) {
        ans.push_back({circ[i][0], circ[i + 1][0]});

        for (int j = 1; j < circ[i + 1].size(); ++j) {
            ans.push_back({circ[i][0], circ[i + 1][j]});
        }

        for (int j = 1; j < circ[i].size(); ++j) {
            ans.push_back({circ[i + 1][0], circ[i][j]});
        }

        ans.push_back({circ[i][0], circ[i + 1][0]});
    }

    if (cnt % 2 == 1) {
        cnt--;
        if (circ[cnt].size() == 2) {
            int pos = 0;
            sort(all(circ[cnt]));
            if (circ[cnt][0] == 0) {
                pos = 1;
                if (circ[cnt][1] == 1) pos = 2;
            }

            ans.push_back({circ[cnt][0], pos});
            ans.push_back({circ[cnt][1], pos});
            ans.push_back({circ[cnt][0], pos});
        } else {

            ans.push_back({circ[cnt][0], circ[cnt][1]});

            for (int i = 2; i + 1 < circ[cnt].size(); ++i) {
                ans.push_back({circ[cnt][0], circ[cnt][i]});
            }

            int x = circ[cnt][0], y = circ[cnt][1], z = circ[cnt][circ[cnt].size() - 1];

            ans.push_back({y, z});
            ans.push_back({x, z});
            ans.push_back({x, y});
        }
    }


    cout << ans.size() << "\n";

    for (int i = 0; i < ans.size(); ++i) {
        cout << ans[i].first + 1 << " " << ans[i].second + 1 << "\n";
    }
}