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);
	}
}