content: package v106;
  
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  public class Friends_UVa10608 {
  
  	public static void main(String[] args) throws IOException {
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  		
  		int tc = sc.nextInt();
  		while(tc-->0)
  		{
  			int n = sc.nextInt(), m = sc.nextInt();
  			UnionFind uf = new UnionFind(n);
  			
  			while(m-->0)
  			{
  				int u = sc.nextInt() - 1, v = sc.nextInt() - 1;
  				uf.unionSet(u, v);
  			}
  			int max = 1;
  			for(int i = 0; i < n; ++i)
  				max = Math.max(max, uf.setSize[i]);
  			out.println(max);
  		}
  		
  		out.flush();
  	}
  	
  	static class UnionFind {                                              
  		int[] p, rank, setSize;
  		int numSets;
  		
  		public UnionFind(int N) 
  		{
  			 p = new int[N];
  			 rank = new int[N];
  			 setSize = new int[N];
  			 numSets = N;
  			 for (int i = 0; i < N; i++) {  p[i] = i; setSize[i] = 1; }
  		}
  		
  		public int findSet(int i) 
  		{ 
  			if (p[i] == i) return i;
  			else return p[i] = findSet(p[i]);
  		 }
  		
  		public Boolean isSameSet(int i, int j) { return findSet(i) == findSet(j); }
  		
  		public void unionSet(int i, int j) 
  		{ 
  			 if (isSameSet(i, j)) 
  				 return;
  			 numSets--; 
  			 int x = findSet(i), y = findSet(j);
  			 // rank is used to keep the tree short
  			 if (rank[x] > rank[y]) { p[y] = x; setSize[x] += setSize[y]; }
  			 else
  			 {	p[x] = y; setSize[y] += setSize[x];
  			 	if(rank[x] == rank[y]) rank[y]++; 
  			 } 
  		}
  		
  		public int numDisjointSets() { return numSets; }
  		
  		public int sizeOfSet(int i) { return setSize[findSet(i)]; }
  	}
  	
  	static class Scanner 
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		public String next() throws IOException 
  		{
  			while (st == null || !st.hasMoreTokens()) 
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {return Integer.parseInt(next());}
  		
  		public long nextLong() throws IOException {return Long.parseLong(next());}
  
  		public String nextLine() throws IOException {return br.readLine();}
  			
  		public boolean ready() throws IOException {return br.ready(); }
  
  
  	}
  }
  