#include <bits/stdc++.h>
using namespace std;
#define _ ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
typedef long long ll ;


int n,m,cnt;
vector<vector<int> > g;
bool vis[10001];
vector<int> v;
void dfs(int u) {
	vis[u] = 1;

	for (int i = 0; i < g[u].size(); i++)
		if (!vis[g[u][i]]){
            cnt++;
			dfs(g[u][i]);
		}
}

int main(){_
 //freopen("Graphs again.in","r", stdin);
    int t;
    cin >> t ;
    while(t--){
	scanf("%d%d", &n, &m);
	g.clear();
	g.resize(n);
	for (int i = 0; i < m; i++) {
		int a, b;
		scanf("%d%d", &a, &b);
		g[a].push_back(b);
		g[b].push_back(a);
	}
	memset(vis, 0, sizeof(vis));
    v.clear();
	for(int i=0;i<n;i++){
            cnt=0;
        if(!vis[i])
            dfs(i);
        v.push_back(cnt);
	}
	sort(v.begin(),v.end(),greater<int>());
	cout << v[0]+v[1] << endl ;
}
}