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>
#define exrep(i, a, b) for(long long i = a; i <= b; i++)
#define rep(i,n)for(long long i=0;i<(long long)(n);i++)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> P;
typedef vector<ll> vl;
typedef vector<string> vs;
typedef vector<P> vp;
typedef vector<vector<ll> > vvl;
typedef vector<vector<P> > vvp;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }
 
const ll MOD=998244353;
const int INF=1e9;
const int MAX=510000;
const double pi=acos(-1);
int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};


int main(){
  cin.tie(0);
  ios::sync_with_stdio(false); 
  
  int n;
  cin >> n;
  vector<ll>a(n);
  rep(i,n){
    ll x;
    cin >> x;
    x--;
    a[x]=i;
  }
  set<int>st;
  st.insert(-1);
  st.insert(n);
  
  ll ans=0;
  rep(i,n){
    auto itr=st.lower_bound(a[i]);
    int r=*itr;
    int l=*(--itr);
    ans+=(a[i]-l)*(r-a[i])*(i+1);
    st.insert(a[i]);
  }
  cout << ans << endl;
  return 0;     
}