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.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.TreeSet;

public class Main {
	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		int n = Integer.parseInt(br.readLine());
		String[] sa = br.readLine().split(" ");
		Obj[] arr = new Obj[n];
		for (int i = 0; i < n; i++) {
			Obj o = new Obj();
			o.i = i;
			o.a = Integer.parseInt(sa[i]);
			arr[i] = o;
		}
		br.close();

		Arrays.sort(arr, (o1, o2) -> o1.a - o2.a);
		TreeSet<Integer> set = new TreeSet<>();
		set.add(-1);
		set.add(n);
		long ans = 0;
		for (Obj o : arr) {
			long l = o.i - set.lower(o.i);
			long r = set.higher(o.i) - o.i;
			ans += l * r * o.a;
			set.add(o.i);
		}
		System.out.println(ans);
	}

	static class Obj {
		int i, a;
	}
}