/// 9. standard template library (STL)

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

signed main(){

    vector<int> vec; // some dynamic length array
    vec.push_back(1); // push something back to the vector
    vec.pop_back(); // pop something back out of the vector
    cin >> vec.at(2); // like arr[2]
    cout << vec[2] << endl; // or use square bracket
    
    stack<int> sta;
    queue<int> que;
    deque<int> dq; // sound like /dik'iu/
    priority_queue<int> pq; // some container adapter using vector
    
    set<int> se; // a set
    multiset<int> mse; // a multi-set
    se.insert(3); // insert something in the set
    se.erase(3); // delete something out of the set
    se.count(3); // if found 3 in the set, return 1; else return 0
    
    int arr[100],n=10;
    vector<int> ve;
    
    sort(arr,arr+n); // sort the array arr[0]~arr[n-1] in increasing order
    sort(arr,arr+n,greater<int>) // decreasing order
    sort(ve.begin(),ve.end()) // vector sorting
    
    pair<int,int> pii; // a pair, just a pair
    cin << pii.first << pii.second;
    cout << pii.second;
    
    /// ** Don't forget to add ';' at the end of the statement **
}