import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static long maximumValue(int[] a) {
        long max = Integer.MIN_VALUE;
        for (int i = 0; i < a.length; i++) {
            for (int j = 0; j < a.length; j++) {
                long gcd = 1;
                long m = a[i] > a[j] ? a[i] : a[j];
                int min = a[i] < a[j] ? a[i] : a[j];
                
                if(m % min == 0) {
                    gcd = min;
                } else {
                for (int k = 2; k < min/2; k++) {
                    if(a[i] % k == 0 && a[j] % k == 0) {
                        gcd = k;
                    }
                }
                }
                long sum = a[i] + a[j];
                
                long val = gcd * (sum - m);
                if(max < val) {
                    max = val;
                }
            }
        }
        return max;
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int a_i = 0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        long result = maximumValue(a);
        System.out.println(result);
        in.close();
    }
}