#include <bits/stdc++.h>
using namespace std;
vector<int> tekijat[10] = {{},
                           {},
                           {2},
                           {2, 3},
                           {2, 3, 2, 2},
                           {2, 3, 2, 2, 5},
                           {2, 3, 2, 2, 5, 2, 3},
                           {2, 3, 2, 2, 5, 2, 3, 7},
                           {2, 3, 2, 2, 5, 2, 3, 7, 2, 2, 2},
                           {2, 3, 2, 2, 5, 2, 3, 7, 2, 2, 2, 3, 3}};
int main() {
  vector<int> o(10);
  int n;
  string a;
  cin >> n >> a;
  for (char c : a) {
    int v = c - '0';
    for (int t : tekijat[v]) o[t]++;
  }
  vector<int> t;
  while (o[7] >= 1 && o[5] >= 1 && o[3] >= 2 && o[2] >= 4) {
    t.push_back(7);
    o[7]--;
    o[5]--;
    o[3] -= 2;
    o[2] -= 4;
  }
  while (o[5] >= 1 && o[3] >= 1 && o[2] >= 3) {
    t.push_back(5);
    o[5]--;
    o[3]--;
    o[2] -= 3;
  }
  while (o[3] >= 1 && o[2] >= 1) {
    t.push_back(3);
    o[3]--;
    o[2]--;
  }
  while (o[2] >= 1) {
    t.push_back(2);
    o[2]--;
  }
  sort(t.rbegin(), t.rend());
  for (int v : t) cout << v;
  cout << '\n';
}
