#include <bits/stdc++.h>
using namespace std;
long long dp[101];
int main() {
  int n;
  scanf("%d", &n);
  dp[0] = 0;
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    dp[i] = dp[i - 1] + 1LL * (x - 1) * i + 1;
  }
  cout << dp[n] << endl;
}
