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

fac = [0 for i in range(10)]
fac[0] = fac[1] = 1
for i in range(2, 10):
    fac[i] = i * fac[i - 1]

def ffactor(x):
    ff = []
    for i in range(2, len(fac)):
        if x > 0 and x % fac[i] == 0:
            ff.append(i)
            x //= fac[i]
        if x == 1:
            break
    if x != 1:
        ff.append(x)
    return ff


n = int(input())
a = input()
sset = []
for num in a:
    k = int(num)
    if k == 1:
        continue
    for i in reversed(range(2, k + 1)):
        ff = ffactor(i)
        if len(ff) == 1:
            sset.append(i)
            break
        sset.extend(ff)

sset = list(sorted(sset, reverse=True))
ret = ''
for i in sset:
    ret += str(i)
print(ret)
