#include <iostream>

#define MAX_VERTEX 1000

class Graph
{
private:
    int n;
    int graph[MAX_VERTEX][MAX_VERTEX];
    int queue[MAX_VERTEX], visitors[MAX_VERTEX];

public:
    void onVisitors(int i) {
        visitors[i] = 1;
    }

    int visit_yet() {
        for(int i = 0; i<n; i++) {
            if(!visitors[i])
                return 0;
        }

        return 1;
    }

    int BFS(int v) {
        int front = 0, rear = 0;
        int noc = 0;
        bool noc_f;

        visitors[v] = 1;
        queue[rear++] = v;
        while(front < rear) {

            v = queue[front++];
            noc_f = false;
            for(int i = 0; i<n; i++) {

                if(graph[v][i] == 1 && !visitors[i]) {
                    visitors[i] = 1;
                    queue[rear++] = i;

                    noc_f = true;
                }
            }

            if(noc_f) noc++;
        }

        return noc;
    }


    void initGraph(int N) {
        n = N;

        for(int i=0; i<n; i++) {

            visitors[i] = 0;

            for(int j=0; j<n; j++) {
                    graph[i][j] = 0;
            }
        }
    }

    int EdgeSum(int iter) {
        int sum = 0;

        for(int i=0; i<n; i++) {
            sum += graph[iter][i];
        }

        return sum;
    }

    void insertEdge(int start, int end) {
        graph[start][end] = 1;
        graph[end][start] = 1;
    }

    int findBiggestEdgeSum() {
        int bigSum = 0;
        int c_bigSum = 0;
        int manyConnectedVertex = 0;

        for(int i=0; i<n; i++) {
            if(visitors[i])
                continue;
            c_bigSum = EdgeSum(i);

            if(bigSum < c_bigSum) {
                bigSum = c_bigSum;
                manyConnectedVertex = i;
            }
        }

        if(bigSum != 0)
            return manyConnectedVertex;

        return -1;
    }

};

int main() {
    int T;
    int g, h;
    int s, e;
    int be;
    int noc=0;
    int k;

    Graph gr;

    std::cin >> T;

    while(T > 0) {
        std::cin >> g >> h;

        gr.initGraph(g);

        for(k=0; k<h; k++) {
            std::cin >> s >> e;

            gr.insertEdge(s, e);
        }

        // 고립상태 방 조사 및 카메라 추가
        for(k=0; k<g; k++) {
            if(gr.EdgeSum(k) == 0) {
                gr.onVisitors(k);
                noc++;
            }
        }


        while(gr.visit_yet() == 0) {
            be = gr.findBiggestEdgeSum();

            if(be >= 0) {
                noc += gr.BFS(be);
            }
        }

        std::cout << noc << "\n";
        noc = 0;
        T--;
    }

    return 0;
}