#include <bits/stdc++.h>
using namespace std;
int main() {
  int noOfQuestions;
  cin >> noOfQuestions;
  vector<int> answers;
  for (int i = 0; i < noOfQuestions; i++) {
    int noOfSolutions;
    cin >> noOfSolutions;
    answers.push_back(noOfSolutions);
  }
  unsigned long long result = 0;
  for (int i = 0; i < answers.size(); i++) {
    result += answers[i];
    for (int j = i + 1; j < answers.size(); j++) {
      result += (answers[j]) - 1;
    }
  }
  cout << result;
  return 0;
}
