#include <bits/stdc++.h>
using namespace std;
int main() {
  int n = 0;
  cin >> n;
  int two = 0;
  int three = 0;
  int five = 0;
  int seven = 0;
  for (int i = 0; i < n; ++i) {
    char digit = '\0';
    cin >> digit;
    switch (digit) {
      case '9':
        three += 2;
      case '8':
        two += 3;
      case '7':
        seven += 1;
      case '6':
        two += 1;
        three += 1;
      case '5':
        five += 1;
      case '4':
        two += 2;
      case '3':
        three += 1;
      case '2':
        two += 1;
      default:
        break;
    }
  }
  auto withdraw = [&](int digit) {
    switch (digit) {
      case 9:
        three -= 2;
      case 8:
        two -= 3;
      case 7:
        seven -= 1;
      case 6:
        two -= 1;
        three -= 1;
      case 5:
        five -= 1;
      case 4:
        two -= 2;
      case 3:
        three -= 1;
      case 2:
        two -= 1;
      default:
        break;
    }
  };
  while (seven) {
    cout << '7';
    withdraw(7);
  }
  while (five) {
    cout << '5';
    withdraw(5);
  }
  while (three) {
    cout << '3';
    withdraw(3);
  }
  while (two) {
    cout << '2';
    withdraw(2);
  }
  cout << endl;
}
