// Created by Armin on 1/12/2025.
// See on https://njudge.hu/problemset/main/NT23_Tablajatek2/

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pp = pair<int, int>;

void convertToTernary(ll n) {
  if (n == 0) return;
  const ll x = n % 3;
  n /= 3;
  if (x < 0) n++;
  convertToTernary(n);
  cout << x;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
    
    int n; cin >> n;
    ll i = 0;
    vector<int> j = {0};
    for (int k = 0; k < n; k++) {
        int x; cin >> x;
        if (x == 0) {
          i++;
          j.push_back(0);
        } else if (x == 1) {
          i++;
          j.push_back(1);
        } else if (x == 2) {
          i++;
          j.push_back(2);
        } else if (x == 3) {
          i--;
          j.pop_back();
        } else if (x == 4) {
          int k = (int) j.size() - 1;
          while (j[k] == 0) {
            j[k] = 2;
            k--;
          }
          j[k]--;
        } else if (x == 5) {
          int k = static_cast<int>(j.size()) - 1;
          while (j[k] == 2) {
            j[k] = 0;
            k--;
          }
          j[k]++;
        }
    }
    cout << i << '\n';
    bool nemvoltigazi = true;
    for (int k = 0; k < j.size(); k++) {
      if (!nemvoltigazi) {
        cout << j[k];
      } else if (j[k] != 0) {
        cout << j[k];
        nemvoltigazi = false;
      }
    }
    
    return 0;
}
// 11
// 110
// 111100000
//

// 100
// 022

// 200
// 122

// 21
//