#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); i ++)
using namespace std;
using ll = long long;
using PL = pair<ll,ll>;
using P = pair<int,int>;
constexpr int INF = 1000000000;
constexpr long long HINF = 1000000000000000;
constexpr long long MOD = 1000000007;//998244353;
constexpr double EPS = 1e-4;
constexpr double PI = 3.14159265358979;

int main() {
    int N; cin >> N;
    vector<ll> A(N);
    rep(i,N) cin >> A[i];

    ll ans = 0;
    rep(i,N) {
        ans += A[i] * (ll)(i + 1) * (ll)(N - i);
    }
    cout << ans << endl;
    return 0;
}