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 printl(l: list):
    for x in l:print(x,end=' ')
    print()

def printd(d: dict):
    for k,v in d.items():print(k,v)
#========================



def solve():
    d=[
        [],
        [],
        [2],
        [3, 2],
        [2,2, 3,2],
        [5, 2,2,3,2],
        [3,2, 5,2,2,3,2],
        [7, 3,2,5,2,2,3,2],
        [2,2,2, 7,3,2,5,2,2,3,2],
        [3,3, 2,2,2,7,3,2,5,2,2,3,2],
    ]
    dd = [[d[i].count(j) for j in range(10)] for i in range(10)]

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

    l=[0 for i in range(10)]
    for x in s:
        for i in range(10):
            l[i]+=dd[int(x)][i]
    
    if l[6]<l[7]:
        l[2]-=l[7]-l[6]
        l[3]-=l[7]-l[6]
        l[6]=l[7]
    
    if l[4]<l[5]:
        l[2]-=2*(l[5]-l[4])
        l[4]=l[5]

    d=0
    for i in range(9,1,-1):
        print(str(i)*(l[i]-d), end='')  
        d=l[i]
    


tt=1
if not tt:
    tt=int(input())
for _ in range(tt):
    solve()