#include <bits/stdc++.h>
using namespace std;
const int maxN = 200;
int a[maxN];
int main() {
  int n, m, f, s;
  long long sum = 0;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < n; i++) sum += (long long)(i + 1) * ((long long)a[i] - 1);
  sum += n;
  cout << sum;
}
