#include <bits/stdc++.h>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<ll> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, ll, ll> t4;
typedef tuple<ll, ll, ll, ll, ll> t5;

#define rep(a,n) for(ll a = 0;a < n;a++)
#define repi(a,b,n) for(ll a = b;a < n;a++)

using namespace std;

static const ll INF = 1e15;

const ll mod = 1000000007;

int main() {
	int n;
	cin >> n;
	vector<ll> vs(n);
	rep(i, n) cin >> vs[i];
	ll sum = 0;
	for (int i = 0; i < n; i++) {
		ll left = i + 1;
		ll right = n - i;
		ll token = left* right* vs[i];
		sum += token;
	}
	cout << sum << endl;
	return 0;
}