import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();

		long m = 0;
		for (int i = 0; i < n; i++) {
			m += a[i];
		}

		long ans = 0;
		long ki = 1;
		for (int i = 0; i < n; i++) {
			long c = a[n - 1 - i] * ki % m;
			ans += c;
			ans %= m;
			ki *= k;
			ki %= m;
		}
		System.out.println(ans);
	}
}