#include <iostream>
//#include <fstream>
#include <deque>

using namespace std;

//ifstream fin("be.in");

long long n, a, i, sor=0, elem=1;
deque <int> v;

int main()
{
    cin>>n;

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

        if (a==0)
        {
            ++sor;
            elem=elem*2-1;
        }else if (a==1)
        {
            ++sor;
            elem=elem*2;
        }else if (a==2)
        {
            --sor;
            elem=elem/2+elem%2;
        }else if(a==3) --elem;
        else ++elem;
    }

    cout<<sor<<"\n";
    --elem;

    while (elem)
    {
        v.push_front(elem%2);
        elem/=2;
    }

    for (auto &e:v)
    {
        cout<<e;
    }

    return 0;
}