#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <climits>
#include <string>
#include <set>
#include <cmath>
#include <map>
#include <unordered_map>
#include <numeric>
#include <random>
#include <memory>
#include <chrono>
#include <iterator>
#include <functional>
#include <unordered_set>
#include <cassert>
#include <cstring>
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x...)
#endif
/*
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
*/
//#define int ll
 
 
 
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;
#define sz(x) int((x).size())
 
#ifndef LOCAL
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
#else
mt19937 rng(228);
#endif
 
const int N = 2e2 + 7;
const int inf = INT_MAX / 2;
const ll INF = LLONG_MAX / 3;
const int MOD = 1e9 + 7;
const double eps = 1e-6;
const string cars[] = {"🚗", "🚕", "🚙"};

vector < int > a;
short n;

unordered_map < int, bool > state[N];

bool solve(int x, int d, short k) {
    if (state[k].find(d) != state[k].end()) {
        return state[k][d];
    }

    if (k == n) {
        state[k][d] = false;
        return false;
    }
    else {
        short j = 0;
        for (int y : a) {
            j += (abs(x - y) % d == 0);
        }

        bool res = false;    
    
        if (j > k) {
            res |= !solve(x, d, k + 1);
        }

        for (int y : a) {
            if (x == y) {
                continue;
            }

            int g = __gcd(abs(x - y), d);
            if (g != 1 && g != d) {
                res |= !solve(x, g, k + 1);
            }
        }

        state[k][d] = res;
        return res;
    }
}

vector < int > solve1() {
    vector < int > ans;
    for (short i = 0; i < n; i++) {
        bool res = false;
        for (int k = 0; k < N; k++) {
            state[k].clear();
        }

        for (short j = 0; j < n; j++) {
            if (i == j) {
                continue;
            }

            if (abs(a[i] - a[j]) > 1) {
                res |= !solve(a[i], abs(a[i] - a[j]), 2);
            }
        }

        if (res ^ 1) {
            ans.push_back(a[i]);
        }
    }
    return ans;
}


signed main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    cout << fixed << setprecision(4);
    ios::sync_with_stdio(false);
    cin.tie();
    cout.tie();

    cin >> n;
    
    a = vector < int > (n);

    for (int& x : a) {
        cin >> x;
    }

    auto ans = solve1();

    cout << sz(ans) << "\n";
    for (int x : ans) {
        cout << x << " ";
    }

    return 0;
}