#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int N = 100'447;
VI g[N];
bool used[N];
int ans;
int mx = 0;

void dfs(int v)
{
	used[v] = 1;
	mx = max(mx, v);
	for (auto to : g[v])
	{
		if (used[to])
			continue;
		if (to != mx + 1 && !used[mx + 1])
		{
			ans++;
			dfs(mx + 1);
		}
		if (used[to])
			continue;
		dfs(to);
	}
}

void solve()
{
	int n, m;
	cin >> n >> m;
	FOR (i, 0, m)
	{
		int u, v;
		cin >> u >> v;
		u--, v--;
		g[u].PB(v);
		g[v].PB(u);
	}
	FOR (i, 0, n)
		sort(ALL(g[i]));
	ans = 0;
	dfs(0);
	FOR (i, 1, n)
	{
		if (!used[i])
		{
			ans++;
			dfs(i);
		}
	}
	cout << ans << '\n';
	mx = 0;
	FOR (i, 0, n)
	{
		g[i].clear();
		used[i] = 0;
	}
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int t;
	cin >> t;
	while (t--)
	{
		solve();
	}
	
	
	return 0;
}