#include <iostream>
#include <set>
#include <stack>

using namespace std;

void solve() {
    int n, m;
    cin >> n >> m;
    set<int> graph[n];
    for (int i = 0, f, t; i < m; ++i) {
        cin >> f >> t;
        f--; t--;
        if (t < f) swap(f, t);
        if (f == t) continue;
        graph[f].insert(t);
        graph[t].insert(f);
    }
    int res = 0;
    int parent[n];
    fill(parent, parent + n, -1);
    for (int s = 0; s < n - 1; ++s) {
        int i = s;
        while (i >= 0) {
            while (!graph[i].empty() && *graph[i].begin() <= s) {
                graph[i].erase(graph[i].begin());
            }
            if (!graph[i].empty()) break;
            i = parent[i];
        }
        if (i < 0) i = 0;
        if (!graph[i].empty() && *graph[i].begin() == s + 1) {
            continue;
        }
        graph[i].insert(s + 1);
        graph[s + 1].insert(i);
        res++;
        parent[s + 1] = i;
    }

    cout << res << endl;
}

int main() {
    int t;
    cin >> t;
    while (t--) solve();

    return 0;
}