#!/bin/python3

import sys
from math import gcd
from itertools import permutations

def maximumValue(a):
    # Return the maximum value of f among all subsegments [l..r].
    b = list(str(x) for x in a)
    maxi = 0
    for x in permutations(b, 2):
        y = list(int(z) for z in x)
        o = sum(y) - max(y)
        m = gcd(y[0], y[1]) * o
        if m > maxi:
            maxi = m
    return maxi        
    

if __name__ == "__main__":
    n = int(input().strip())
    a = list(map(int, input().strip().split(' ')))
    result = maximumValue(a)
    print(result)