Language: C++

#include <bits/stdc++.h>
#define ll          long long
#define pb          push_back
#define pii         pair<int,int>
#define vi          vector<int>
#define vii         vector<pii>
#define mi          map<int,int>
#define mii         map<pii,int>
#define all(a)      (a).begin(),(a).end()
#define ff           first
#define ss           second
#define sz(x)       (int)x.size()
#define endl        '\n'
#define hell        1000000007
#define rep(i,a,b)  for(int i=a;i<b;i++)
using namespace std;

// Most important thing in CP - Have Fun :)

const int maxn = 200005;
int parent[maxn];
int size[maxn];

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(){
	//write here
    int n,m;
    for (int i = 0 ; i<n ; i++)make_set(i);
    cin>>n>>m;
    for (int i = 0 ; i<m ; i++){
        int u,v;
        cin>>u>>v;
        u--;v--;
        union_sets(u,v);
    }
    int mxval = 0;
    for (int i = 0 ; i<n ; i++)mxval = max(mxval,size[i]);
    cout<<mxval<<endl;
}

int main(){
	cin.tie(NULL);
	ios::sync_with_stdio(false);
	//insert code
	
		solve();
	return 0;
}

Compiler output:
a.cc: In function 'void make_set(int)':
a.cc:26:5: error: reference to 'size' is ambiguous
   26 |     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: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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~
a.cc: In function 'void union_sets(int, int)':
a.cc:37:13: error: reference to 'size' is ambiguous
   37 |         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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~
a.cc:37:23: error: reference to 'size' is ambiguous
   37 |         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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~
a.cc:40:9: error: reference to 'size' is ambiguous
   40 |         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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~
a.cc:40:20: error: reference to 'size' is ambiguous
   40 |         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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~
a.cc: In function 'void solve()':
a.cc:56:50: error: reference to 'size' is ambiguous
   56 |     for (int i = 0 ; i<n ; i++)mxval = max(mxval,size[i]);
      |                                                  ^~~~
/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:22:5: note:                 'int size [200005]'
   22 | int size[maxn];
      |     ^~~~