#include <bits/stdc++.h>
using namespace std;
int n;
char s[20];
int a[20];
int f[20][10];
int req[10];
int b[10] = {0, 2, 3, 5, 7};
int main() {
  for (int i = 1; i <= 4; i++) f[0][i] = 0;
  for (int i = 1; i <= 9; i++) {
    for (int j = 1; j <= 4; j++) f[i][j] = f[i - 1][j];
    int p = i;
    while (p % 2 == 0) {
      p = p / 2;
      f[i][1]++;
    }
    while (p % 3 == 0) {
      p = p / 3;
      f[i][2]++;
    }
    while (p % 5 == 0) {
      p = p / 5;
      f[i][3]++;
    }
    while (p % 7 == 0) {
      p = p / 7;
      f[i][4]++;
    }
  }
  scanf("%d", &n);
  gets(s);
  gets(s);
  for (int i = 1; i <= n; i++) {
    a[i] = s[i - 1] - '0';
    for (int j = 1; j <= 4; j++) req[j] += f[a[i]][j];
  }
  for (int i = 4; i >= 1; i--) {
    while (req[i]) {
      putchar(b[i] + 48);
      for (int j = 1; j <= 4; j++) req[j] -= f[b[i]][j];
    }
  }
  return 0;
}
