#include <bits/stdc++.h>
using namespace std;
int N, M, T;
long long s[127], k, Mc;
int main() {
  int i, j;
  scanf("%d", &T);
  for (i = 1; i <= T; i++) {
    scanf("%I64d", &k);
    s[i] = (k - 1) * i + 1;
    Mc += s[i];
  }
  printf("%I64d\n", Mc);
  scanf(" ");
}
