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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main()
{
    ll n, ans;
    vector<ll> a;

    cin >> n;
    for (ll i = n; i--;) {
        ll t;
        cin >> t;
        a.push_back(t);
    }

    for (int i = 1; i < n; ++i) {
        for (ll j: a) {
            ans += j;
        }

        vector<ll> b;
        for (unsigned j = 0; j < a.size() - 1; ++j) {
            b.push_back(min(a[j], a[j + 1]));
        }

        a = b;
    }

    ans += a[0];

    cout << ans << endl;

    return 0;
}