#include <bits/stdc++.h>
using namespace std;
int n;
string s;
int a[10];
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> s;
  for (int i = 0; i < n; i++) a[s[i] - '0']++;
  a[2] += a[9] + a[8] * 3 + 2 * a[4];
  a[3] += 2 * a[9] + a[6] + a[4];
  a[5] += a[6];
  a[6] = a[4] = 0;
  a[7] += a[8] + a[9];
  for (int k = 7; k >= 2; k--) {
    for (int i = 1; i <= a[k]; i++) {
      cout << k;
    }
  }
  cout << endl;
  return 0;
}
