#include <bits/stdc++.h>

using namespace std;
int gcd(int a, int b)
{
   
    if (a == 0 || b == 0)
       return 0;
 
   
    if (a == b)
        return a;
 
    
    if (a > b)
        return gcd(a-b, b);
    return gcd(a, b-a);
}
long maximumValue(vector <int> a) {
    int l=a.size();
    int g=0,max=0,sum=0;
    long res=0;
    for(int i=0;i<l;i++)
    {
        for(int j=i;j<l;j++)
        {
           g=gcd(abs(a[i]),abs(a[j]));
           if(a[i]>a[j])
               max=a[i];
            else
                max=a[j];
            if(i!=j)
            sum=a[i]+a[j];
            else
            sum=a[i];
            //cout<<a[i]<<" "<<a[j]<<endl;
            //cout<<g<<" "<<max<<" "<<sum<<endl;
            int tmp=g*(sum-max);
            //cout<<tmp<<" ";
            if(tmp>res)
                res=tmp;
        }
    }
    return res;
    // Return the maximum value of f among all subsegments [l..r].
}

int main() {
    int n;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0; a_i < n; a_i++){
       cin >> a[a_i];
    }
    long result = maximumValue(a);
    cout << result << endl;
    return 0;
}