Language: C++

/*Arnab's Code
*/
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define vll vector<ll>
#define vii vector<int>
#define pll pair<ll,ll>
#define pii pair<int,int>/*Arnab's Code
*/
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp(a,b) make_pair(a,b)
#define vll vector<ll>
#define vii vector<int>
#define pll pair<ll,ll>
#define pii pair<int,int>
#define take(a,n) for(ll i=0;i<n;i++)cin>>a[i]
#define takes(a,n,st) for(ll i=st;i<n+st;i++)cin>>a[i]
ll sum(ll a[],ll n,ll s){ for(ll i=0;i<n;i++)s+=a[i]; return s;}
#define mod 1000000009
ll power(ll x, ll y, ll p)  {  
    ll res = 1;  
    x = x % p;   
    if (x == 0) return 0;  
    while (y > 0){  
        if (y & 1)  
            res = (res*x) % p;  
        y = y>>1;
        x = (x*x) % p;  
    }  
    return res;  
}
int parent[200017];
int size[200017];
void make_set(int v) {
    parent[v] = v;
    size[v] = 1;
}

int find_set(int v) {
    if (v == parent[v])
        return v;
    return parent[v] = find_set(parent[v]);
}

void union_sets(int a, int b) {
    a = find_set(a);
    b = find_set(b);
    if (a != b) {
        if (size[a] < size[b])
            swap(a, b);
        parent[b] = a;
        size[a] += size[b];
    }
}
void solve(){
	ll n,m,i,x,y;
	cin>>n>>m;
	for(i=0;i<=n;i++)
		make_set(i);
	for(i=0;i<m;i++){
		cin>>x>>y;
		union_sets(x,y);
	}
	cout<<*max_element(size,size+n+1);
	return;
}
int main(){
	ios::sync_with_stdio(false);
	cin.tie(NULL);
	#ifndef ONLINE_JUDGE
		freopen("input.txt","r",stdin);
		freopen("output.txt","w",stdout);
	#endif
	ll t,T;
//	cin>>T;
	T=1;
	for(t=1;t<=T;t++){
//		cout<<"Case #"<<t<<": ";
		solve();
	}
	return 0;
}


Compiler output:
a.cc: In function 'void make_set(int)':
a.cc:42:5: error: reference to 'size' is ambiguous
   42 |     size[v] = 1;
      |     ^~~~
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52,
                 from a.cc:3:
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc: In function 'void union_sets(int, int)':
a.cc:55:13: error: reference to 'size' is ambiguous
   55 |         if (size[a] < size[b])
      |             ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc:55:23: error: reference to 'size' is ambiguous
   55 |         if (size[a] < size[b])
      |                       ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc:58:9: error: reference to 'size' is ambiguous
   58 |         size[a] += size[b];
      |         ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc:58:20: error: reference to 'size' is ambiguous
   58 |         size[a] += size[b];
      |                    ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc: In function 'void solve()':
a.cc:70:28: error: reference to 'size' is ambiguous
   70 |         cout<<*max_element(size,size+n+1);
      |                            ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~
a.cc:70:33: error: reference to 'size' is ambiguous
   70 |         cout<<*max_element(size,size+n+1);
      |                                 ^~~~
/usr/include/c++/14/bits/range_access.h:272:5: note: candidates are: 'template<class _Tp, long unsigned int _Nm> constexpr std::size_t std::size(const _Tp (&)[_Nm])'
  272 |     size(const _Tp (&)[_Nm]) noexcept
      |     ^~~~
/usr/include/c++/14/bits/range_access.h:262:5: note:                 'template<class _Container> constexpr decltype (__cont.size()) std::size(const _Container&)'
  262 |     size(const _Container& __cont) noexcept(noexcept(__cont.size()))
      |     ^~~~
a.cc:39:5: note:                 'int size [200017]'
   39 | int size[200017];
      |     ^~~~