#include <bits/stdc++.h>
using namespace std;
int n, a[105];
long long ans = 0;
int main(int argc, char **argv) {
  scanf("%d", &n);
  for (int i = 1; i <= n; ++i) {
    scanf("%d", &a[i]);
    ans += a[i] + (long long)(a[i] - 1) * (i - 1);
  }
  printf("%lld\n", ans);
  return 0;
}
