#include <bits/stdc++.h>
using namespace std;
void doit() {
  long long n;
  long long a[101], res;
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  res = 0;
  for (long long i = 1; i <= n; i++) res += (i - 1) * (a[i] - 1) + a[i];
  cout << res << endl;
  return;
}
int main() {
  doit();
  return 0;
}
