#include <iostream>

 #include <vector>

 using namespace std;

 const int N = ;

 int V;

 vector<int> adj[];

 vector<bool> visited;

 const int UNWATCHED = ;

 const int  WATCHED = ;

 const int INSTALLED = ;

 int installed;

 int dfs(int here)

 {

     visited[here] = true;

     int children[] = { ,, };

     for (int i = ; i < adj[here].size(); i++)

     {

         int there = adj[here][i];

         if (!visited[there])

             ++children[dfs(there)];

     }

     //后代节点存在没有监视的节点 在该节点安装摄像头

     if (children[UNWATCHED]) {

         ++installed;

         return INSTALLED;

     }

     if (children[INSTALLED]) {

         return WATCHED;

     }

     return UNWATCHED;

 }

 int installCamera()

 {

     installed = ;

     visited = vector<bool>(V, false);

     for (int u = ; u < V; ++u) {

         if (!visited[u] && dfs(u) == UNWATCHED)

             ++installed;

     }

     return installed;

 }

 /*

 3

 6 5

 0 1

 1 2

 1 3

 2 5

 0 4

 4 2

 0 1

 2 3

 1000 1

 0 1

 =====================

 3

 2

 999

 */

 int main()

 {

     int sampleCount = ;

     cin >> sampleCount;

     while (sampleCount--) {

         int n, m; visited.clear();

         for (int i = ; i < ; i++) adj[i].clear();

         cin >> V >> m;

         for (int i = ; i < m; i++) {

             int a, b;

             cin >> a >> b;

             adj[a].push_back(b);

             adj[b].push_back(a);

         }

         cout << installCamera() << endl;

     }

     return ;

 }