#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, a[111], c = 0;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  c = a[0];
  for (int i = 1; i < n; i++) {
    if (a[i] > 1)
      c = c + (i * (a[i] - 1)) + (a[i]);
    else
      c = c + 1;
  }
  cout << c;
}
