basic operations:

1. Pre-processor derivative: # include<bits/stdc++.h> , #include<iostream>

2. standard library usage: using namespace std;

3. important data types:

   • vector: vector\<int\> v;
   • unordered map: `unordered_map<string, int> umap;
   • ordered map: map<int, int> order;

4. Operations on vector: v.push_back(x); , v.pop_back();

5. output all the vector elements: for(int i = 0; i < v.size(); i++) cout<<v[i]<<"\n";

6. sort: sort(v.begin(), v.end());