#include <bits/stdc++.h>
using namespace std;
long long a[105], ans;
int n;
int main() {
  cin >> n;
  for (long long i = 1; i <= n; i++) {
    cin >> a[i];
    ans += (a[i] - 1ll) * i;
  }
  ans += (long long)n;
  cout << ans << endl;
}
