// Marcin Knapik
#include<bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
using namespace std;

// #include <ext/pb_ds/assoc_container.hpp> // order_of_key
// #include <ext/pb_ds/tree_policy.hpp> // find by order
// using namespace __gnu_pbds;
// #define ordered_set tree< pair<int, int> , null_type,less<pair<int, int>>, rb_tree_tag,tree_order_statistics_node_update>

// const ll MAX_LL = 0xFFFFFFFFFFFFFFFF;
// mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// #define losuj(a, b) uniform_int_distribution<ull>(a, b)(rng)

typedef long double             ld;
typedef long long               ll;
typedef unsigned long long      ull;
typedef pair<ll, ll>            pll;
typedef pair<int, int>          ii;
typedef vector<int>             vi;
typedef vector<ii>              vii;
typedef vector<vi>              vvi;
typedef vector<vector<ii>>      vvii;
typedef vector< ll >            vll;
typedef vector< pll >           vpll;

#define boost                   ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define sz(a)                   (int)(a).size()
#define pb                      push_back
#define all(c)                  (c).begin(), (c).end()
#define rall(c)                 (c).rbegin(), (c).rend()
#define REP(i, a, b)            for (int i = (a); i <= (b); i++)
#define FOR(i, a)               for (int i = 0; i < (a); i++)
#define TRAV(i, n)              for(auto&i:n)
#define beg(x)                  (*(x.begin()))
#define re(x)                   int x; cin >>x;
#define f                       first
#define s                       second

template <class T> inline bool setmin(T &a, T b){if (a > b)return a = b, 1;return 0;}
template <class T> inline bool setmax(T &a, T b){if (a < b)return a = b, 1;return 0;}

template<class T> inline T fast(T a,T b,T mod) {ll res = 1; while(b){if(b&1) res = (res*a)%mod;a = (a*a)%mod;b >>= 1;}return res;}
template<class T> inline T russian(T a, T b, T mod) {ll res = 0; while(b){if(b&1) res = (res + a)%mod; a = (a+a)%mod; b>>=1;}return res;}
template <class T> istream &operator>>(istream &os, vector<T> &container){for (auto &u : container)os >> u;return os;}
template <class T> ostream &operator<<(ostream &os, const vector<T> &container){for (auto &u : container)os << u << " ";return os;}
template<typename T> inline T gcd(T a, T b) { while (b)swap(a %= b, b); return a; }

const ll INF = 1e9 + 7;
const ll mod = 998244353;
const ll BIG_INF = 1e18 + 7;
const ll N = 1e6+7;
const ll T = 1<<19;


ll n, m, q;

int tab[N];

int main(){
	ios::sync_with_stdio(0);
	cin.tie(0);

	cin >> n;
	vi ans;
	FOR(i, n){
		int temp;
		cin >> temp;
		ans = {temp};
		tab[temp]++;
	}

	for(int i = 1; i < N; i++){
		if(tab[i] > 1){
			int suma = 0;
			int kon = i;

			while(tab[kon] > 1){
				suma += tab[kon];
				kon++;
			}

			kon--;
			vi temp = {};
			if(tab[i-1] > 0){
				temp.pb(i-1);
			}
			for(int j = i; j <= kon; j++){
				temp.pb(j);
			}
			if(tab[kon+1]){
				temp.pb(kon+1);
			}
			for(int j = kon; j >= i; j--){
				for(int k = 0; k < tab[j]-1; k++){
					temp.pb(j);
				}
			}

			if(sz(temp) > sz(ans)){
				ans = temp;
			}

			i = kon;
		}
	}

	if(sz(ans) == 1){
		for(int i = 1; i < N-4; i++){
			if(tab[i] && tab[i+1]){
				cout << 2 << '\n';
				cout << i << ' ' << i+1 << '\n';
				exit(0);
			}
		}
	}
	cout << sz(ans) << '\n';
	cout << ans << '\n';
}