import java.util.*; public class Main { public static void main (String[] args) { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int[] arr = new int[n]; for (int i = 0; i < n; i++) { arr[i] = sc.nextInt(); } long ans = 0; for (int i = 0; i < n; i++) { long left = i + 1; long right = n - i; ans += arr[i] * left * right; } System.out.println(ans); } }