#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[1001], n;
  cin >> n;
  int s = 0;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
    s += a[i] * i;
  }
  cout << s << endl;
  return 0;
}
