#include <bits/stdc++.h>
using namespace std;
const int N = 55;
typedef long long LL;
int n;
int w[N];
vector<int>f[N][N];
bool cmp(vector<int>& a, vector<int>& b)
{
    if (a.size() != b.size())return a.size() < b.size();
    for (int i = a.size() - 1; i >= 0; i--)
    {
        if (a[i] != b[i])
            return a[i] < b[i];
    }
    return true;
}
vector<int>add(vector<int>a, vector<int>b)
{
    vector<int>c;
    int t = 0;
    for (int i = 0; i < (int)a.size() || i < (int)b.size(); i++)
    {
        if (i < (int)a.size())t += a[i];
        if (i < (int)b.size())t += b[i];
        c.push_back(t % 10);
        t /= 10;
    }
    while (t)
    {
        c.push_back(t % 10);
        t /= 10;
    }
    return c;
}
vector<int>mul(vector<int>a, LL b)
{
    vector<int>c;
    LL t = 0;
    for (int i = 0; i < (int)a.size(); i++)
    {
        t += a[i] * b;
        c.push_back(t % 10);
        t /= 10;
    }
    while (t)
    {
        c.push_back(t % 10);
        t /= 10;
    }
    return c;
}
int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)cin >> w[i];
    for (int len = 3; len <= n; len++)
    {
        for (int l = 1; l + len - 1 <= n; l++)
        {
            int r = l + len - 1;
            for (int k = l + 1; k < r; k++)
            {
                auto val = mul(mul({ w[l] }, w[k]), w[r]);
                val = add(add(val, f[l][k]), f[k][r]);
                if (f[l][r].empty() || cmp(val, f[l][r]))f[l][r] = val;
            }
        }
    }
    auto res = f[1][n];
    for (int i = res.size() - 1; i >= 0; i--)
        cout << res[i];
    cout << endl;
    return 0;
}