#include <bits/stdc++.h>
using namespace std;

int main()
{
	long long N;
	cin >> N;
	vector<long long> A( N );
	for( int i = 0; i < N; i++ ) {
		cin >> A[i];
	}

	long long ans = 0;
	for( long long i = 0; i < N; i++ ) {
		ans += A[i] * (i + 1) * (N - i);
	}

	cout << ans << endl;
}