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