样例过，交上去只对 Subtask #6 一个点。

#include <bits/stdc++.h>
#define N 2 * 114514
using namespace std;
int T, n, m, s1, s2;
bool i1[N], i2[N];

signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> T;
	while (T--) {
		cin >> n >> m;
		int ans = -1;
		s1 = s2 = 0;
		memset(i1, 0, sizeof i1);
		memset(i2, 0, sizeof i2);
		int i = 0;
		while (m--) {
			i++;
			int type, num;
			cin >> type >> num;
			if (type == 1) {
				s1++;
				i1[num] = 1;
				if (s1 == n && ans == -1) ans = i;
				if (i2[num] && ans == -1) ans = i;
			} else {
				s2++;
				i2[num] = 1;
				if (s2 > 1 && ans == -1) ans = i;
				if (i1[num] && ans == -1) ans = i;
			}
		}
		cout << ans << "\n"; 
	}
    return 0;
}