#include <iostream>

using namespace std;

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	int N, A, i;
	long long sum = 0;
	cin >> N;
	
	for (i = 0; i != N; ++i)
		cin >> A, sum += A * static_cast<long long>(i + 1) * (N - i);

	cout << sum << '\n';
	return 0;
}