#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>

typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;





int main()
{

    int Q;
    Q = 1;
    //cin >> Q;


    while (Q--) {
        int n;
        cin >> n;
        vector<ll>x(n);
        for (int i = 0; i < n; i++)cin >> x[i];
        ll r = 0;
        for(int i=0;i<n;i++)
            for (int j = i + 1; j < n; j++) {
                r += abs(j - i) * abs(x[j] - x[i]);
            }
        cout << r*2 << endl;
    }
    return 0;
}