/*
#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
//*/

#include <bits/stdc++.h>

// #include <atcoder/all>
// #include <atcoder/maxflow>

using namespace std;
// using namespace atcoder;

#define DEBUG(x) cerr << #x << ": " << x << endl;
#define DEBUG_VEC(v)                                        \
    cerr << #v << ":";                                      \
    for (int iiiiiiii = 0; iiiiiiii < v.size(); iiiiiiii++) \
        cerr << " " << v[iiiiiiii];                         \
    cerr << endl;
#define DEBUG_MAT(v)                                \
    cerr << #v << endl;                             \
    for (int iv = 0; iv < v.size(); iv++) {         \
        for (int jv = 0; jv < v[iv].size(); jv++) { \
            cerr << v[iv][jv] << " ";               \
        }                                           \
        cerr << endl;                               \
    }
typedef long long ll;
// #define int ll

#define vi vector<int>
#define vl vector<ll>
#define vii vector<vector<int>>
#define vll vector<vector<ll>>
#define vs vector<string>
#define pii pair<int, int>
#define pis pair<int, string>
#define psi pair<string, int>
#define pll pair<ll, ll>
template <class S, class T>
pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) {
    return pair<S, T>(s.first + t.first, s.second + t.second);
}
template <class S, class T>
pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template <class S, class T>
ostream &operator<<(ostream &os, pair<S, T> p) {
    os << "(" << p.first << ", " << p.second << ")";
    return os;
}
#define X first
#define Y second
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep1(i, n) for (int i = 1; i <= (int)(n); i++)
#define rrep(i, n) for (int i = (int)(n)-1; i >= 0; i--)
#define rrep1(i, n) for (int i = (int)(n); i > 0; i--)
#define REP(i, a, b) for (int i = a; i < b; i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(), c.end()
void YES(bool t = true) {
    cout << (t ? "YES" : "NO") << endl;
}
void Yes(bool t = true) { cout << (t ? "Yes" : "No") << endl; }
void yes(bool t = true) { cout << (t ? "yes" : "no") << endl; }
void NO(bool t = true) { cout << (t ? "NO" : "YES") << endl; }
void No(bool t = true) { cout << (t ? "No" : "Yes") << endl; }
void no(bool t = true) { cout << (t ? "no" : "yes") << endl; }
template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const long double pi = 3.1415926535897932384626433832795028841971L;
int popcount(ll t) { return __builtin_popcountll(t); }
// int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
// int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
vi dx = {0, 1, 0, -1}, dy = {-1, 0, 1, 0};
vi dx2 = {1, 1, 0, -1, -1, -1, 0, 1}, dy2 = {0, 1, 1, 1, 0, -1, -1, -1};
struct Setup_io {
    Setup_io() {
        ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
        cout << fixed << setprecision(25);
    }
} setup_io;
const ll MOD = 1000000007;
// const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

template <typename T>
class SegmentTree {
  public:
    using F = function<T(T &, T &)>;
    int n;
    vector<T> dat;
    T e; // �P�ʌ�
    F query_func;
    F update_func;

    SegmentTree(vector<T> a, F query_func, F update_func, T e) : n(a.size()), query_func(query_func), update_func(update_func), e(e) {
        if (n == 0) {
            a.push_back(e);
            n++;
        }
        dat.resize(4 * n);
        init(0, 0, n, a);
    }

    void init(int k, int l, int r, vector<T> &a) {
        if (r - l == 1) {
            dat[k] = a[l];
        } else {
            int lch = 2 * k + 1, rch = 2 * k + 2;
            init(lch, l, (l + r) / 2, a);
            init(rch, (l + r) / 2, r, a);
            dat[k] = query_func(dat[lch], dat[rch]);
        }
    }

    //k�Ԗڂ̒l��a�ɕύX
    void update(int k, T a, int v, int l, int r) {
        if (r - l == 1) {
            dat[v] = update_func(dat[v], a);
        } else {
            if (k < (l + r) / 2)
                update(k, a, 2 * v + 1, l, (l + r) / 2);
            else {
                update(k, a, 2 * v + 2, (l + r) / 2, r);
            }
            dat[v] = query_func(dat[v * 2 + 1], dat[v * 2 + 2]);
        }
    }

    //[a,b)�̍ŏ��l�����߂�
    //���̂ق��̈����͌v�Z�̊ȒP�̂��߂̈���
    //k�͐ړ_�̔ԍ�,l,r�͂��̐ړ_��[l,r)�ɑΉ����Ă��邱�Ƃ�\��
    //�]���āA�O�����query(a,b,0,0,n)�Ƃ��Ă��
    T query(int a, int b, int k, int l, int r) {
        if (r <= a || b <= l) {
            return e;
        }
        if (a <= l && r <= b) {
            return dat[k];
        } else {
            T ul = query(a, b, k * 2 + 1, l, (l + r) / 2);
            T ur = query(a, b, k * 2 + 2, (l + r) / 2, r);
            return query_func(ul, ur);
        }
    }

    T query(int a, int b) {
        return query(a, b, 0, 0, n);
    }

    // �����𖞂����ĉE��T��
    int find(int a, int b, int k, int l, int r, int x) {
        // �����𒼂�
        if (dat[k] < x || r <= a || b <= l) return -1;
        if (l + 1 == r) {
            // �����𒼂�
            if (dat[k] >= x)
                return l;
            else
                return -1;
        }
        int rv = find(a, b, 2 * k + 2, (l + r) / 2, r, x);
        if (rv != -1) return rv;
        return find(a, b, 2 * k + 1, l, (l + r) / 2, x);
    }
};

pii f(pii a, pii b) {
    if (a.first != b.first)
        return max(a, b);
    else
        return min(a, b);
}

pii g(pii a, pii b) { return b; }

vi lis(vi p) {
    int n = p.size();

    vector<pii> ini(n + 1, pii(-inf, -inf));
    ini[0] = pii(0, -1);
    SegmentTree<pii> seg(ini, f, g, pii(-inf, -inf));

    vi pre(n);
    rep(i, n) {
        int x = p[i];
        pii ma = seg.query(0, x, 0, 0, seg.n);
        pre[i] = ma.second;

        ma.first++;
        ma.second = i;
        seg.update(x, ma, 0, 0, seg.n);
    }

    int ans = seg.query(0, n + 1).first;
    int start;
    rep(i, n) {
        int x = p[i];
        if (seg.query(x, x + 1).first == ans) {
            start = i;
            break;
        }
    }

    vi res;
    while (start != -1) {
        res.push_back(start);
        start = pre[start];
    }
    // DEBUG_VEC(res);

    return res;
}

signed main() {
    int n;
    cin >> n;
    vi p(n);
    rep(i, n) {
        cin >> p[i];
    }

    vi head = lis(p);

    vi q(n);
    rep(i, n) {
        q[i] = p[n - 1 - i];
        q[i] = n + 1 - q[i];
    }

    vi tail = lis(q);

    // assert(seg1.query(0, n + 1, 0, 0, seg1.n) == seg2.query(0, n + 1, 0, 0, seg2.n));

    // int ma = seg1.query(0, n + 1, 0, 0, seg1.n);

    // vi s1o(n + 1), s2o(n + 1);
    // rep(i, n) {
    //     s1o[p[i]] = seg1.query(i, i + 1);
    //     s2o[q[i]] = seg1.query(i, i + 1);
    // }
    assert(head.size() == tail.size());

    vi cnt(n);
    rep(i, head.size()) {
        cnt[head[i]]++;
        tail[i] = n - 1 - tail[i];
        cnt[tail[i]]++;
    }

    int ans = 0;
    rep(i, n) {
        if (cnt[i] == 2) {
            ans++;
        }
    }

    cout << ans << endl;
    rep(i, n) {
        if (cnt[i] == 2) {
            cout << p[i] << " ";
        }
    }
    cout << endl;
}