#include <bits/stdc++.h>
using namespace std;
int ABS(int _x) { return _x > 0 ? _x : -_x; }
int main() {
  int N;
  long long a[105], res[105];
  cin >> N;
  for (int(i) = (0); (i) < (N); (i)++) cin >> a[i];
  res[0] = a[0];
  for (int(i) = (1); (i) < (N); (i)++) {
    res[i] = res[i - 1] + (long long)(i + 1) * (long long)(a[i] - 1) + 1LL;
  }
  cout << res[N - 1] << endl;
  return 0;
}
