#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 25;
char st[MAX_N];
int digit_num[10];
int n;
int main() {
  scanf("%d", &n);
  scanf("%s", st);
  for (int i = 0; i < n; i++) {
    int temp = st[i] - '0';
    digit_num[temp]++;
  }
  digit_num[2] += digit_num[9];
  digit_num[3] += digit_num[9] * 2;
  digit_num[7] += digit_num[9];
  digit_num[9] = 0;
  digit_num[2] += digit_num[8] * 3;
  digit_num[7] += digit_num[8];
  digit_num[8] = 0;
  digit_num[3] += digit_num[6];
  digit_num[5] += digit_num[6];
  digit_num[6] = 0;
  digit_num[2] += digit_num[4] * 2;
  digit_num[3] += digit_num[4];
  digit_num[4] = 0;
  for (int i = 9; i > 1; i--) {
    for (int j = 0; j < digit_num[i]; j++) {
      putchar(i + '0');
    }
  }
  puts("");
  return 0;
}
