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.
def isprime(n) : 
 
    # Corner cases 
    if (n <= 1) : 
        return False
    if (n <= 3) : 
        return True
 
    # This is checked so that we can skip 
    # middle five numbers in below loop 
    if (n % 2 == 0 or n % 3 == 0) : 
        return False
 
    i = 5
    while(i * i <= n) : 
        if (n % i == 0 or n % (i + 2) == 0) : 
            return False
        i = i + 6
 
    return True
 

n = int(input())
s = input()

arr = [int(i) for i in s]
ans = []

tmp = []
for i in range(n):
    
    if arr[i]==1:
        continue
    
    elif not isprime(arr[i]):
        
        if arr[i]==6:
            ans.append(5)
            tmp.extend([3,2])
        elif arr[i]==4:
            ans.append(3)
            tmp.extend([2,2])
        elif arr[i]==9:
            ans.append(7)
            tmp.extend([3,3,2,2,2])
        elif arr[i]==8:
            ans.append(7)
            tmp.extend([2,2,2])
            
    else:
        ans.append(arr[i])
        
tmp.sort(reverse = True)

while(tmp and tmp[0]==3):
    ans.append(tmp.pop(0))
    tmp.pop(-1)
    
ans.sort(reverse = True)
if tmp:
    ans.extend(tmp)
    
tt = [str(i) for i in ans]
x = ''.join(tt)

print(max(int(s),int(x)))
            
            
