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