Drazil is playing a math game with Varda.

Let's define <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/7020b94c48be2ee5b8eeca05f379c8911bb0e7c4.png" style="max-width: 100.0%;max-height: 100.0%;"/> for positive integer *x* as a product of factorials of its digits. For example, <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/6784d861d9a724d0aeddefcb00b7d0c3442ae586.png" style="max-width: 100.0%;max-height: 100.0%;"/>.

First, they choose a decimal number *a* consisting of *n* digits that contains at least one digit larger than 1. This number may possibly start with leading zeroes. Then they should find maximum positive number *x* satisfying following two conditions:

1. *x* doesn't contain neither digit 0 nor digit 1.

2. <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/7020b94c48be2ee5b8eeca05f379c8911bb0e7c4.png" style="max-width: 100.0%;max-height: 100.0%;"/> = <img align="middle" class="tex-formula" src="https://espresso.codeforces.com/aa57e017a6c74d06b0a54bc47e3f6990e5af38c1.png" style="max-width: 100.0%;max-height: 100.0%;"/>.

Help friends find such number.
The first line contains an integer *n* (1 ≤ *n* ≤ 15) — the number of digits in *a*.

The second line contains *n* digits of *a*. There is at least one digit in *a* that is larger than 1. Number *a* may possibly contain leading zeroes.
import math
from typing import List

class Solution:
    def __init__(self, target: int, factorials: List[int]):
        self.target = target
        self.factorials = factorials
        self.ans = None
        self.found = False

    def backtrack(self, curr_num: List[int], target: int):
        if self.ans is not None:
            return

        if target == 1:
            self.ans = curr_num


        for i, fac in self.factorials:
            if target % fac == 0:
                self.backtrack([*curr_num, i], target // fac)


    def compute_max(self):
        self.backtrack([], self.target)

    

n = int(input())
a = input()

target = 1

for digit in a:
    target *= math.factorial(int(digit))

factorials = [[i, math.factorial(i)] for i in range(2, 10)]

solution_obj = Solution(target, factorials)
solution_obj.compute_max()
solution_obj.ans.sort(reverse = True)
print(''.join(str(digit) for digit in solution_obj.ans))

