uva1468

#include <iostream>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <queue>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
#include <algorithm>
#include <numeric>
#include <chrono>
#include <ctime>
#include <cmath>
#include <cctype>
#include <string>
#include <cstdio>
#include <iomanip>


#include <thread>
#include <mutex>
#include <condition_variable>
#include <functional>
#include <iterator>
using namespace std;

const int maxn = 6e4 + 7;
int m, n,h[maxn];
pair<int, int> a, b;
int main()
{
    
	int t,x,y;
	cin >> t;
	while (t--) {
    
		memset(h, 0x3f3f3f3f, sizeof(h));
		cin >> m >> n;
		cin >> a.first >> a.second;
		cin >> b.first >> b.second;

		for (int i = 3; i <= n; i++) {
    
			cin >> x >> y;
			if (x < a.first || x > b.first) continue;
			h[x] = min(h[x],abs(y - a.second) - 1);
		}

		h[a.first] = -1;
		for (int i = a.first + 1; i < b.first; i++) h[i] = min(h[i - 1] + 1, h[i]);
		h[b.first] = -1;
		for (int i = b.first - 1; i > a.first; i--) h[i] = min(h[i + 1] + 1, h[i]);
		long long int ans = 0;
		for (int i = a.first + 1; i < b.first; i++) {
    
			if (h[i] == -1) continue;
			int high = min(a.second + h[i], m - 1);
			int low = max(a.second - h[i], 0);
			ans += high - low + 1;
		}
		cout << ans << endl;
	}
	return 0;
}