#include<iostream>
#include<vector>
#include<algorithm>
#include<bitset>
using namespace std;

const int VMAX = 5e4 + 1;

bitset<VMAX> putem;

class InParser {
    vector<char> str;
    int ptr;
    ifstream fin;

    char getChar() {
        if (ptr == int(str.size())) {
            fin.read(str.data(), str.size());
            ptr = 0;
        }
        return str[ptr++];
    }

    template<class T>
    T getInt() {
        char chr = getChar();
        while (!isdigit(chr) && chr != '-')
            chr = getChar();
        int sgn = +1;
        if (chr == '-') {
            sgn = -1;
            chr = getChar();
        }
        T num = 0;
        while (isdigit(chr)) {
            num = num * 10 + chr - '0';
            chr = getChar();
        }
        return sgn * num;
    }

public:
    InParser(const char* name) : str(1e5), ptr(str.size()), fin(name) { }
    ~InParser() { fin.close(); }

    template<class T>
    friend InParser& operator>>(InParser& in, T& num) {
        num = in.getInt<T>();
        return in;
    }
};

class OutParser {
    vector<char> str;
    int ptr;
    ofstream fout;

    void putChar(char chr) {
        if (ptr == int(str.size())) {
            fout.write(str.data(), str.size());
            ptr = 0;
        }
        str[ptr++] = chr;
    }

    template<class T>
    void putInt(T num) {
        if (num < 0) {
            putChar('-');
            num *= -1;
        }
        if (num > 9)
            putInt(num / 10);
        putChar(num % 10 + '0');
    }

public:
    OutParser(const char* name) : str(1e5), ptr(0), fout(name) { }
    ~OutParser() { fout.write(str.data(), ptr); fout.close(); }

    template<class T>
    friend OutParser& operator<<(OutParser& out, const T num) {
        out.putInt(num);
        return out;
    }

    friend OutParser& operator<<(OutParser& out, const char chr) {
        out.putChar(chr);
        return out;
    }

    friend OutParser& operator<<(OutParser& out, const char* str) {
        for (int i = 0; str[i]; i++)
            out.putChar(str[i]);
        return out;
    }
};

int main()
{
    InParser cin("economie.in");
    OutParser cout("economie.out");

    int n; cin >> n;
    vector<int> v(n);

    for(int i = 0; i < n ; i++) cin >> v[i];
    sort(v.begin(),v.end());

    vector<int> ans;
    putem[0] = 1;
    for(auto it : v)
        {
            if(putem[it])
                continue;

            ans.push_back(it);
            for(int i = it; i < VMAX ; i++)
                {
                    if(putem[i])
                        continue;

                    if(putem[i - it])
                        putem[i] = 1;
                }
        }

    cout << ans.size() << '\n';
    for(auto it : ans)
        cout << it << " ";

    return 0;
}