#include <bits/stdc++.h>
using namespace std;
const int inf = 1000000009;
int rd() {
  char c = getchar();
  int t = 0, f = 1;
  while (!isdigit(c)) f = (c == '-') ? -1 : 1, c = getchar();
  while (isdigit(c)) t = t * 10 + c - 48, c = getchar();
  return t * f;
}
void wt(int x) {
  if (x > 9) wt(x / 10);
  putchar(x % 10 + 48);
  return;
}
int n;
char str[50];
int num[20];
int main() {
  n = rd();
  scanf("%s", str + 1);
  for (int i = ((int)1); i <= ((int)n); i++) num[str[i] - 48]++;
  num[3] += num[4], num[2] += num[4] * 2;
  num[4] = 0;
  num[5] += num[6], num[3] += num[6];
  num[6] = 0;
  num[2] += 3 * num[8], num[7] += num[8];
  num[8] = 0;
  num[2] += num[9], num[3] += num[9] * 2, num[7] += num[9];
  for (int i = ((int)8); i >= ((int)2); i--)
    while (num[i]--) putchar(i + 48);
  return 0;
  return 0;
}
