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.
all_premiers_numbers = [2, 3, 5, 7]

# function that returns the decomposition of a number with its factorial
def decompose_number(number):
    if(number in all_premiers_numbers):
        return [number]
    elif number == 4:
        return [3, 2, 2]
    elif number == 6:
        return [3, 5]
    elif number == 8:
        return [2, 2, 2, 7]
    else:
        return [3, 3, 2, 7]

def main():
    n = int(input())
    a = int(input())
    my_list = []
    for chiffre in str(a):
        if((int(chiffre) != 1) and (int(chiffre) != 0)):
            my_list += decompose_number(int(chiffre))

    my_list.sort()
    my_list.reverse()
    final_result = ""
    if(my_list == []):
        print(a)
    else:
        for number in my_list:
            final_result += str(number)
        print(final_result)


main()