#include <bits/stdc++.h>
using namespace std;
long long a[110];
int main() {
  int i, n;
  long long ans;
  while (scanf("%d", &n) != EOF) {
    for (i = 0; i < n; ++i) cin >> a[i];
    for (ans = i = 0; i < n; ++i) {
      ans += (a[i] - 1) * (i + 1) + 1;
    }
    cout << ans << endl;
  }
  return 0;
}
