largest size of connected component

#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll max_ll(ll x, ll y){
return ((x>y)?(x):(y));
}
int main()
{
    ll n,m;
    cin>>n>>m;
    vector<ll> adj[n+1];
    map <pair<ll,ll>,ll> mp;
    for (ll i=1; i<=m; i++){
        ll x,y;
        cin>>x>>y;
        if ((x>=y && mp[make_pair(x,y)]<1) || (x<y && mp[make_pair(y,x)]<1)){
            adj[x].push_back(y);
            adj[y].push_back(x);
            if (x>=y) mp[make_pair(x,y)]++;
            else mp[make_pair(y,x)]++;
        }
    }
    ll groups=0, ans=0;
    vector <bool> visited(n+1,false);
    for (ll i=1; i<=n; i++){
        if(!visited[i]){
            visited[i]=true;
            groups++;
            queue <ll> q;
            q.push(i);
            while(!q.empty()){
                ll v=q.front();
                q.pop();
                for (auto u:adj[v]){
                    if (!visited[u]){
                        visited[u]=true;
                        groups++;
                        q.push(u);
                    }
                }
            }
        }
        ans=max_ll(ans,groups);
        groups=0;
    }
    cout<<ans<<"\n";
}