paulami-and-the-factorials
Source: hackerearth
Difficulty: MEDIUM

Paulami is playing a math game with Aparajita.

Let's define F(x) for positive integer x as a product of factorials of its digits. For example, F(135)=1! * 3! * 5! =720.

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:
x doesn't contain neither digit 0 nor digit 1.
F(x)=F(a) .

Help friends find such number.

Input

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.

Output

Output a maximum possible integer satisfying the conditions above. There should be no zeroes and ones in this number decimal representation.

SAMPLE INPUT
4
1234

SAMPLE OUTPUT
33222

Explanation

In the sample test case,
F(1234) = 1! * 2! * 3! * 4! = 288 = F(33222)