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>
using namespace std;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define MIN(a) *min_element(all(a))
#define MAX(a) *max_element(all(a))
#define SUM(a, b) accumulate(all(a), b)
#define REP(i, n) for(int (i)=0; (i)<(n); (i)++)
#define RREP(i, n) for(int (i)=(n)-1; (i)>=0; (i)--)
#define FOR(i, m, n) for(int (i)=(m); (i)<(n); i++)
#define FORR(i, m, n) for(int (i)=(n)-1; (i)>=(m); i--)
#define ios() cin.tie(0), ios::sync_with_stdio(false)
#define debug(x) cerr << #x << " = " << x << endl
//#define int long long

typedef long long ll;
typedef unsigned long long ull;
//ll const MOD = 998244353;
ll const MOD = 1e9+7;
ll const INF = 1e18;

template<typename T> int size(const T& a){return (int)a.size();}
template<typename T> T Div(T a, T b){return (a + b - 1) / b;}
template<typename T> bool chmin(T& a, const T& b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, const T& b){if(a < b){a = b; return true;} return false;}



signed main(){
    ios();
    int n;
    cin >> n;
    vector<int> v(n);
    REP(i, n){
        int a;
        cin >> a;
        v[a-1] = i+1;
    }
    
    ll ans = 0;
    set<int> st;
    st.insert(0);
    st.insert(n+1);

    REP(i, n){
        int p = v[i];
        auto itr = st.upper_bound(p);
        int r = *itr;
        itr--;
        int l = *itr;
        ans += (ll)(i+1) * (r-p)*(p-l);
        st.insert(p);
    }

    cout << ans << endl;
    
    return 0;
}