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