#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;

bool mark[60000]={false};
vector<ll>store[60000];

ll cnt=0;

ll bfs(ll n)
{
    queue<ll>q;
    q.push(n);
    mark[n]=true;
    cnt=1;
    while(!q.empty())
    {
        ll x=q.front();
        q.pop();
        for(auto i: store[x])
        {
            if(mark[i]==false)
            {
                q.push(i);
                mark[i]=true;
                cnt++;
            }
        }
    }
    return cnt;
}


int main()
{
    ll i,j,k,x,y,m,n,t,a,b,c,d,e,cas=1;
    cin>>t;
    while(t--)
    {
        cin>>n>>m;
        cnt=0;
        for(i=1; i<=n; i++)
            mark[i]=false;
        for(i=1; i<=n; i++)
            store[i].clear();
        for(i=0; i<m; i++)
        {
            cin>>x>>y;
            store[x].push_back(y);
            store[y].push_back(x);
        }
        ll res=-1;
        for(i=1; i<=n; i++)
        {
            if(mark[i]==false)
            {
                a=bfs(i);
                res=max(res,a);
            }

        }

        cout<<res<<endl;
    }
    return 0;
}