#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; }