#include <bits/stdc++.h>
using namespace std;
const long long MAXN = 105;
long long N;
long long A[MAXN];
long long Ans;
int main() {
  scanf("%lld", &N);
  for (long long i = 1; i <= N; i++) {
    scanf("%lld", &A[i]);
  }
  for (long long i = 1; i <= N; i++) {
    Ans = Ans + (A[i] - 1) * (i - 1) + A[i];
  }
  printf("%lld\n", Ans);
  return 0;
}
