#include <iostream>
#include <cstdint>
#include <vector>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	
	uint32_t N, i, j;
	cin >> N;
	vector<uint32_t> A(N);
	for (i = 0; i != N; ++i) cin >> A[i];

	uint64_t ans = 0;
	vector<uint64_t> index_csum(501, 0);
	vector<uint32_t> count(501, 0);
	for (i = 0; i != N; ++i)
	{
		++count[A[i]], index_csum[A[i]] += i;
		for (j = 1; j != A[i]; ++j)
			ans += (static_cast<uint64_t>(count[j]) * i - index_csum[j]) * (A[i] - j);
		for (++j; j != 501; ++j)
			ans += (static_cast<uint64_t>(count[j]) * i - index_csum[j]) * (j - A[i]);
	}

	cout << (ans << 1) << '\n';
	return 0;
}