Language: C++

/*" بِسْمِ اللهِ الرَّحْمٰنِ الرَّحِيْمِ -In the name of Allah."
   Never stop chasing!-MD.SOURAV.

   ░░░░░░░░( •̪●)░░░░░░░░░░░░░░░░░░░░░░░░
   ░░░░░░███████ ]▄▄▄▄▄▄▄▄▃░░░▃░░░░ ▃░
   ▂▄▅█████████▅▄▃▂░░░░░░░░░░░░░░░░░
   [███████████████████].░░░░░░░░░░░░░░
   ◥⊙▲⊙▲⊙▲⊙▲⊙▲⊙▲⊙◤...░░░░░░░░░░░░
*/

#include <bits/stdc++.h>


#define endl           "\n"
#define MAX            32000
#define F              first
#define S              second
#define sz(x)          x.size()
#define li             long int
#define gcd(a,b)       _gcd(a,b)
#define pb             push_back
#define mp             make_pair
#define asrt(a,n)      sort(a,a+n)
#define MOD 	       1000000007
#define ll             long long int
#define lcd(a,b)       (a*b)/gcd(a,b)
#define mp(x,y)        make_pair(x,y)
#define no             cout<<"NO"<<endl
#define yes            cout<<"YES"<<endl
#define f(i, a, n)     for(int i=a;i<n;i++)
#define test           int t;cin>>t;while(t--)
#define srt(v)         sort(v.begin() , v.end())
#define basrt(a,n)     sort(a,a+n, greater<int>())
#define deb(x)         cout << #x<< ": "<< x<< endl;
#define sumof(x)       accumulate(x.begin(),x.end(),0);
#define rsrt(v)        sort(v.begin(),v.end(),greater<int>())
#define enter(v,n)     for(ll i=0;i<n;i++){ll x;cin>>x;v.pb(x);}
#define unique(v)      v.erase(unique(v.begin(),v.end()),v.end())
#define start          ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define ignore         cin.ignore (std::numeric_limits<std::streamsize>::max(),'\n');



using namespace std;

double pi=3.14159265358979323846264338327950288419716939937510582097494459230781640628620899862803482534211706798214808651328230664 ;
typedef vector<ll> vll;
typedef vector<int> vii;
typedef map<ll,ll> mllll;
typedef map<char,ll> mchll;
typedef map<string,ll> msll;
typedef vector<pair<ll,ll>> vpllll;
typedef vector<pair<int,int>> vpiiii;

template<typename T>
ostream& operator<<(ostream &os, const vector<T> &v)
{
    os << '{';
    for (const auto &x : v) os << " " << x;
        return os << '}';
}

vector<int>v[2];


void solve()
{

    int n,m,cnt;
    cin >> n >> m;
	vector< set<ll> > v(n);
	int a,b;
	for(int i=0;i<m;i++)

		cin>>a>>b;
		a--;
		b--;
		v[a].insert(b);
		v[b].insert(a);
	}
	vector<int>dist(n);
	int Max=0;
	for(int i=0;i<n;i++)
    {
        if(dist[i]!=0)
        {
            continue;
        }
        queue<int>que;
        dist[i]=1;
        que.push(i);
        int sum=1;

        while(!que.empty())
        {
            int p=que.front();
            que.pop();

            for(auto np:v[p])
            {
                if(dist[np]!=0)
                {
                    continue;
                }
                dist[np]=1;
                sum+=1;
                que.push(np);
            }
        }
        Max=max(sum,Max);
    }
    cout << Max << endl;











}

int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    ll test_case=1;
    //cin>>test_case;
    while(test_case--)
	{
		solve();
	}

	return 0;
}


Compiler output:
a.cc:27:9: warning: "mp" redefined
   27 | #define mp(x,y)        make_pair(x,y)
      |         ^~
a.cc:22:9: note: this is the location of the previous definition
   22 | #define mp             make_pair
      |         ^~
a.cc:81:25: error: 'n' was not declared in this scope; did you mean 'yn'?
   81 |         vector<int>dist(n);
      |                         ^
      |                         yn
a.cc:83:9: error: expected unqualified-id before 'for'
   83 |         for(int i=0;i<n;i++)
      |         ^~~
a.cc:83:21: error: 'i' does not name a type; did you mean 'li'?
   83 |         for(int i=0;i<n;i++)
      |                     ^
      |                     li
a.cc:83:25: error: 'i' does not name a type; did you mean 'li'?
   83 |         for(int i=0;i<n;i++)
      |                         ^
      |                         li
a.cc:112:5: error: 'cout' does not name a type
  112 |     cout << Max << endl;
      |     ^~~~
a.cc:124:1: error: expected declaration before '}' token
  124 | }
      | ^