Problem:
Score : 400 points

Problem Statement

One day, Snuke was given a permutation of length N, a_1, a_2, ..., a_N, from his friend.

Find the following:

Constraints

1 ≦ N ≦ 200,000

(a_1, a_2, ..., a_N) is a permutation of (1, 2, ..., N).

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the answer.

Note that the answer may not fit into a 32-bit integer.

Sample Input 1

3
2 1 3

Sample Output 1

9

Sample Input 2

4
1 3 2 4

Sample Output 2

19

Sample Input 3

8
5 4 8 1 2 6 7 3

Sample Output 3

85

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.TreeSet;

public class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {
		int N = sc.nextInt();
		int[] A = new int[N];
		int[] P = new int[N + 1];
		for (int i = 0; i < N; ++i) {
			A[i] = Integer.parseInt(sc.next());
			P[A[i]] = i;
		}
		long ans = 0;
		TreeSet<Integer> used = new TreeSet<>();
		used.add(-1);
		used.add(N);
		for (int i = 1; i <= N; ++i) {
			int pos = P[i];
			int lo = used.lower(pos);
			int hi = used.higher(pos);
			ans += (long) i * (pos - lo) * (hi - pos);
			used.add(pos);
		}
		System.out.println(ans);
	}
}