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