#include <bits/stdc++.h>
using namespace std;
long long n;
long long a[110];
int main() {
  ios::sync_with_stdio(0);
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> a[i];
  long long ans = 0;
  for (long long i = 0; i < n; ++i) {
    ans += (a[i] - 1) * (i + 1) + 1;
  }
  cout << ans << "\n";
}
