#include <iostream>
#include <vector>
#include <set>
using namespace std;
using vi = vector<int>;

void solve() {
	int n, m; cin >> n >> m;
	vector<set<int, greater<int>>> adj(n+1);
	vi vis(n+1);
	for (int i = 0; i < m; i++) {
		int u, v; cin >> u >> v;
		adj[u].insert(v);
		adj[v].insert(u);
	}
	vi st;

	st.push_back(1);
	int out = 0;
	while (st.size()) {
		int top = st.back();
		st.pop_back();
		if (top == n) break;
		vis[top] = true;
		vi nex = {adj[top].begin(), adj[top].end()};
		for (int i : nex) {
			if (vis[i]) {
				adj[top].erase(i);
				adj[i].erase(top);
			}
		}
		if (st.size() && adj[top].size() == 0 && st.back() == top+1) continue;
		if (adj[top].count(top+1) == 0) {
			adj[top].insert(top+1);
			adj[top+1].insert(top);
			out++;
		}
		for (int i : adj[top]) st.push_back(i);
	}
	cout << out << endl;
}

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