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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#include <map>
#include <set>
#include <vector>
#include <algorithm>
#include <iostream>
#include <bitset>
#include <cassert>
#include <queue>
#include <random>
#include <stack>
#include <iomanip>
#include <math.h>
using namespace std;
#define rep(i, n) for (ll i = 0; i < (ll)n; i++)
#define repf(i, a, b) for (ll i = (ll)a; i < (ll)b; i++)
#define repr(i, a, b) for (ll i = (ll)a; i > (ll)b; i--)
#define repv(x, arr) for (auto &x : arr)
#define all(v) (v).begin(), (v).end()
#define vec(name, num) vector<ll> name((num), 0);
#define mp(a, b) make_pair(a, b)
#define pb(x) push_back(x)
#define F first
#define S second
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pdd;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef vector<int> vii;
typedef vector<vii> vvii;
const ll mod = 1e9 + 7;
const int infi = 2147483600;
const ll infl = 1e17;

int main()
{
    int n;cin>>n;
    vll a(n);
    map<ll, ll> idx;
    rep(i, n){
        cin >> a[i];
        idx[a[i]] = i;
    }
    multiset<ll> exist;
    exist.insert(-1);
    exist.insert(n);
    ll ans = 0;
    repf(i,1,n+1){
        auto itr = exist.lower_bound(idx[i]);
        int l,r;
        r = *itr;
        itr--;
        l = *itr;
        exist.insert(idx[i]);
        ans += i * (r - idx[i]) * (idx[i] - l);
    }
    cout << ans << endl;
}