#include <bits/stdc++.h>
using namespace std;
int n;
long long a[110], sum;
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%lld", &a[i]);
  for (int i = 0; i < n; i++) sum += a[i] + (a[i] - 1) * i;
  printf("%lld\n", sum);
  return 0;
}
