taskA.cpp

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include <map>
#include <string>
#include <cstring>
//#include <unordered_map>
#include <queue>
#include <algorithm>

using namespace std;

#define INF (1<<30)
#define F first
#define S second
#define mkp(a, b) make_pair(a, b)

int s(long long x)
{
    if(x < 10)
        return x;
    int sum = 0;
    while(x)
    {
        sum += x % 10;
        x /= 10;
    }
    return s(sum);
}


int main()
{
    freopen("tickets.in", "r", stdin);
    freopen("tickets.out", "w", stdout);

    int n;
    vector<long long> a;
    vector< vector< long long > > mp(10);
    vector<long long> ans;

    cin >> n;
    a.resize(n);
    for(int i = 0; i < n; i++)
    {
        cin >> a[i];
        mp[s(a[i])].push_back(a[i]);
    }

    while(mp[3].size() > 1)
    {
        ans.push_back(mp[3].back());
        mp[3].pop_back();
        ans[ans.size() - 1] *= mp[3].back();
        mp[3].pop_back();
    }
    while(mp[2].size() && mp[4].size())
    {
        ans.push_back(mp[2].back() * mp[4].back());
        mp[2].pop_back(); mp[4].pop_back();
    }
    while(mp[2].size() > 2)
    {
        ans.push_back(mp[2].back()); mp[2].pop_back();
        ans[ans.size() - 1] *= mp[2].back(); mp[2].pop_back();
        ans[ans.size() - 1] *= mp[2].back(); mp[2].pop_back();
    }
    while(mp[2].size() && mp[3].size())
    {
        ans.push_back(mp[2].back() * mp[3].back());
        mp[2].pop_back(); mp[3].pop_back();
    }
    for(int i = 2; i < 10; i++)
        for(int j = 0; j < mp[i].size(); j++)
            ans.push_back(mp[i][j]);

    sort(ans.begin(), ans.end());

    cout << ans.size() << endl;
    for(int i = 0; i < ans.size(); i++)
        cout << ans[i] << " ";
    return 0;
}