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 (GCC 5.4.1) (judge verdict: Accepted)

#include<stdio.h>
#include<stdlib.h>
#define ll long long
#define rep(i,l,r)for(ll i=(l);i<(r);i++)
#define min(p,q)((p)<(q)?(p):(q))
#define INF ((1LL<<62)-(1LL<<31))

ll a[200010];
ll left[200010],right[200010];

int main(){
	int n;
	scanf("%d",&n);
	rep(i,0,n)scanf("%lld",a+i);
	rep(i,0,n){
		ll temp=i-1;
		while(temp!=-1&&a[temp]>a[i])temp=left[temp];
		left[i]=temp;
	}
	for(int i=n-1;i>=0;i--){
		ll temp=i+1;
		while(temp!=n&&a[temp]>a[i])temp=right[temp];
		right[i]=temp;
	}
	ll ans=0;
	rep(i,0,n)ans+=a[i]*(i-left[i])*(right[i]-i);
	printf("%lld\n",ans);
	return 0;
}