#include <bits/stdc++.h>
using namespace std;
int a[101];
int main() {
  int n, ans = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  for (int i = 1; i <= n; i++) ans += i * a[i];
  cout << ans;
  return 0;
}
