#include <bits/stdc++.h>
using namespace std;
template <class T>
void displayVec(vector<T> &v) {
  for (long long i = 0; i < v.size(); i++) cout << v[i] << " ";
  cout << endl;
}
template <class T>
void displayPq(priority_queue<T> &g) {
  while (!g.empty()) {
    cout << g.top() << " ";
    g.pop();
  }
  cout << '\n';
}
template <class T>
void displayPqg(priority_queue<T, vector<T>, greater<T>> &g) {
  while (!g.empty()) {
    cout << g.top() << " ";
    g.pop();
  }
  cout << '\n';
}
void solve() {
  long long n, i, j, ele, flag = 0, counter, sum = 0;
  vector<long long> vec1;
  cin >> n;
  for (long long i = 0; i < n; i++) {
    cin >> ele;
    vec1.push_back(ele);
  }
  while (!vec1.empty()) {
    ele = vec1.back();
    vec1.pop_back();
    sum += ele + flag;
    flag += ele - 1;
  }
  cout << sum;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  return 0;
}
