#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:64000000")
using namespace std;
const int INF = (int)1E9;
const long long INF64 = (long long)1E18;
const long double EPS = 1E-8;
const long double PI = 3.1415926535897932384626433832795;
const int MAXN = 110;
int n;
long long a[MAXN];
int main() {
  cin >> n;
  for (int i = 0; i < (int)(n); i++) cin >> a[i];
  long long ans = 0;
  for (int i = 0; i < (int)(n); i++) ans += (i + 1) * (a[i] - 1);
  cout << ans + n << endl;
  return 0;
}
