#include <bits/stdc++.h>
using namespace std;
long long int powmod(long long int a, int b, int n) {
  long long int rm = 1;
  while (b) {
    if (b % 2) {
      rm = (rm * a) % n;
    }
    a = (a * a) % n;
    b /= 2;
  }
  return rm;
}
int main() {
  int n;
  long long int a[110];
  cin >> n;
  for (int i = (int)1; i <= (int)n; i++) cin >> a[i];
  long long int cost = 0;
  for (long long int i = 1; i <= n; ++i) {
    cost = cost + (a[i] - 1) * i + 1;
  }
  cout << cost << endl;
  return 0;
}
