Here is the link of the problem https://cses.fi/problemset/task/1621/

And this is my code

```
int main()
{
ll n;
cin >> n;
unordered_set<int> s;
for (int i = 0; i < n; i++)
{
ll x;
cin >> x;
s.insert(x);
}
cout << s.size() << endl;
}
```

I have time limit in one of the test cases