#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef long double ld;
typedef pair<int,int> P;
typedef pair<ll, int> PL;
constexpr ll INF = (1LL << 60);

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

  ll l = 0;

  ll res = 0;
 
  for (int i = 0; i < n; i++) {
    ll r = n - i;
    res += l * r * a[i] + a[i] * r;
    l++;
  }
  cout << res << endl;
  return 0;
}