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 C# (Mono 4.6.2.0) (judge verdict: Time Limit Exceeded)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

class Program
{
    static void Main(string[] args)
    {
        int N = int.Parse(Console.ReadLine());
        int[] a = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        int[] pos = new int[N + 1];
        for (int i = 0; i < N; ++i) { pos[a[i]] = i; }
        var list = new SortedSet<int>();
        list.Add(-1);
        list.Add(N);
        long sum = 0;
        for (int i = 1; i <= N; ++i)
        {
            int p = pos[i];
            int L = list.Where(n => n < p).Max();
            int R = list.Where(n => n > p).Min();
            sum += Math.BigMul(p - L, R - p) * i;
            list.Add(p);
        }
        Console.WriteLine(sum);
    }
}