#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  long long q[101];
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) cin >> q[i];
  long long sum = 0;
  for (int i = 1; i <= n; i++) {
    sum += q[i] + (q[i] - 1) * (i - 1);
  }
  cout << sum << endl;
  return 0;
}
