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.
input()
a_str = input()

def factorial(x):
    if x == 0:
        return 0
    f = 1
    for i in range(2, x + 1):
        f *= i
    return f

def populate_primes(n, primes):
    while n > 1:
        for k in primes.keys():
            while n % k == 0:
                primes[k] += 1
                n //= k


primes = {2: 0, 3: 0, 5: 0, 7: 0}
retrieval = {
    2: {2: 1},
    3: {2: 1, 3: 1},
    5: {2: 3, 3: 1, 5: 1},
    7: {2: 4, 3: 2, 5: 1, 7: 1}
}


for m in a_str:
    mfp = factorial(int(m))
    populate_primes(mfp, primes)


order_primes = list(primes.keys())
order_primes.sort(reverse=True)


r_str = ''
for p in order_primes:
    while primes[p] > 0:
        for k in primes.keys():
            if k <= p:
                primes[k] -= retrieval[p][k]
        r_str += str(p)

print(r_str)
