#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = 10 * x + ch - '0';
    ch = getchar();
  }
  return x * f;
}
int a[10];
int main() {
  int n = read();
  for (int i = 1; i <= (n); i++) {
    char ch = getchar();
    while (ch < '0' || ch > '9') ch = getchar();
    a[ch - '0']++;
  }
  for (int i = (9); i >= (1); i--) {
    if (i == 9) {
      a[3] += 2 * a[9];
      a[7] += a[9];
      a[2] += a[9];
      a[9] = 0;
    } else if (i == 8) {
      a[7] += a[8];
      a[2] += 3 * a[8];
      a[8] = 0;
    } else if (i == 6) {
      a[3] += a[6];
      a[5] += a[6];
      a[6] = 0;
    } else if (i == 4) {
      a[2] += 2 * a[4];
      a[3] += a[4];
      a[4] = 0;
    }
  }
  for (int i = (9); i >= (2); i--)
    for (int j = 1; j <= (a[i]); j++) putchar('0' + i);
  printf("\n");
  return 0;
}
