#include <bits/stdc++.h>
using namespace std;
long long int a[110];
long long int ans = 0;
int main() {
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) ans = ans + i * (a[i] - 1) + 1;
  cout << ans;
  return 0;
}
