#include <bits/stdc++.h>
using namespace std;
int main(){
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  long long ans = 0;
  for (int i = 0; i < N; i++){
    ans += (long long) (i + 1) * (N - i) * A[i];
  }
  cout << ans << endl;
}