Monotonic

#include <bits/stdc++.h>

#define ll long long
#define lll __int128
#define pii pair<int, int>
#define M 1000000007
#define N 101
#define PB push_back
#define F first
#define S second
using namespace std;

int solve(){
	int n, m;
	cin>>n>>m;
	pii p[m];
	for (int i = 0; i < m; i++) {
		cin>>p[i].F>>p[i].S;
		p[i].F--;
		p[i].S--;
	}
	vector<int> t;
	for (int i = 0; i < n; i++) t.push_back(n - i);
	int ans = 0;
	bool sr = true;
	for (int i = 0; i < n; i++) {
		if (i) sr &= t[i] > t[i - 1];
	}
	while (!sr) {
		ans++;
		
		for (int i = 0; i < m; i++) {
			if (t[p[i].F] > t[p[i].S]) swap(t[p[i].F], t[p[i].S]);
		}
		
		sr = true;
		for (int i = 1; i < n; i++) {
			if (i) sr &= t[i] > t[i - 1];
		}
		if (ans == n * n) return -1;
	}
	return ans;
	
}

int main () {
	ll t; cin >> t;
	while(t--) cout << solve() << "\n";
}

/**
AAU
YBA
BTY
*/

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED