// tablajatek.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <queue>
#define ll long long

using namespace std;

ll sz = 0, n, i, a, j;
deque <ll>x;

int main()
{
    cin >> n;
    for (i = 1; i <= n; ++i)
    {
        cin >> a;

        if (a == 0)
        {
            x.push_back(0);
            sz = sz + 1;
        }

        if (a == 1)
        {
            x.push_back(1);
            sz = sz + 1;
        }

        if (a == 2)
        {
            x.pop_back();
            --sz;
        }

        if (a == 3)
        {
            j = x.size() - 1;
            while (j >= 0 && x[j]==0)
            {
                x[j] = 1;
                --j;
            }
            if (j >= 0) x[j] = 0;
        }

        if (a == 4)
        {
            j = x.size() - 1;
            while (j >= 0 && x[j] == 1)
            {
                x[j] = 0;
                --j;
            }
            if (j >= 0) x[j] = 1;
        }
    }

    cout << sz << " " << endl;

    if(x.empty()) cout << "0";
    else for (auto& e : x) cout << e;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file