Rating Change = K × (Actual Score - Expected Score)

Where:
- K depends on your rating and contest participation
- New accounts have higher K (faster rating changes)
- Expected score based on your current rating vs opponents

┌─────────────────────────────────────────────┐
│  1. Register for the contest                │
│  2. Check your template compiles            │
│  3. Have input.txt ready                    │
│  4. Close distracting tabs                  │
│  5. Get water/snacks ready                  │
└─────────────────────────────────────────────┘

Problems     → List of all problems
Standings    → Real-time leaderboard
Submit       → Submit your solution
My Submissions → Check verdicts

┌─────────────────────────────────────────────────────┐
│  PROBLEM TITLE                                      │
├─────────────────────────────────────────────────────┤
│  Time limit: 1 second                               │
│  Memory limit: 256 megabytes                        │
├─────────────────────────────────────────────────────┤
│  [Story/Context - often skip-able]                  │
│                                                     │
│  [Actual problem statement - READ CAREFULLY]        │
│                                                     │
│  [Constraints - VERY IMPORTANT]                     │
├─────────────────────────────────────────────────────┤
│  Input                                              │
│  [Input format description]                         │
│                                                     │
│  Output                                             │
│  [Output format description]                        │
├─────────────────────────────────────────────────────┤
│  Examples                                           │
│  Input:         Output:                             │
│  3              6                                   │
│  1 2 3                                              │
├─────────────────────────────────────────────────────┤
│  Note                                               │
│  [Explanation of examples - very helpful!]          │
└─────────────────────────────────────────────────────┘

class Solution:
    def solve(self, nums: List[int]) -> int:
        return sum(nums)

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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int n;
    cin >> n;
    
    vector<int> nums(n);
    for (int i = 0; i < n; i++) {
        cin >> nums[i];
    }
    
    long long sum = 0;
    for (int x : nums) sum += x;
    
    cout << sum << "\n";
    
    return 0;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int t;
    cin >> t;
    
    while (t--) {
        // Solve one test case
        int n;
        cin >> n;
        // ... solution ...
        cout << answer << "\n";
    }
    
    return 0;
}

Input:
5
1 2 3 4 5

int n;
cin >> n;
vector<int> a(n);
for (int& x : a) cin >> x;

Input:
3 4
1 2 3 4
5 6 7 8
9 10 11 12

int n, m;
cin >> n >> m;
vector<vector<int>> grid(n, vector<int>(m));
for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++)
        cin >> grid[i][j];

Input:
3 3
...
.#.
...

int n, m;
cin >> n >> m;
vector<string> grid(n);
for (int i = 0; i < n; i++) cin >> grid[i];
// Access: grid[i][j]

Input:
4 5
1 2
2 3
3 4
4 1
1 3

int n, m;
cin >> n >> m;
vector<vector<int>> adj(n + 1);
for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back(v);
    adj[v].push_back(u);  // If undirected
}

Input:
5 3
1 2 3 4 5
1 3
2 4
1 5

int n, q;
cin >> n >> q;
vector<int> a(n);
for (int& x : a) cin >> x;

while (q--) {
    int l, r;
    cin >> l >> r;
    // Process query [l, r]
}

// Always check problem for exact format
cout << (condition ? "YES" : "NO") << "\n";
// Some problems want "Yes"/"No" or "yes"/"no"

if (impossible) {
    cout << -1 << "\n";  // or "NO" or "Impossible"
    return;
}

cout << fixed << setprecision(9) << answer << "\n";

cout << a << " " << b << " " << c << "\n";

// Array output
for (int i = 0; i < n; i++) {
    cout << arr[i] << " \n"[i == n - 1];
}

// Generate random test
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n = rng() % 10 + 1;
vector<int> a(n);
for (int& x : a) x = rng() % 100;