import java.util.Scanner;

public class Main {
	static int fun(Scanner sc) {
		int n, m;
		int res = -1;
		int k = 0;
		n = sc.nextInt();// n个杯子
		m = sc.nextInt();// m次操作
		boolean[] a = new boolean[n];
		boolean[] v = new boolean[n];

		for (int i = 0; i < m; i++) {
			int o, x;
			o = sc.nextInt();
			x = sc.nextInt();
			if (res != -1)
				continue;
			if (o == 1) {
				if (a[x - 1] == false) {
					a[x - 1] = true;
					k++;
					if (k == n) {
						res = i + 1;
					}
				}
			} else {// o==2

				if (v[x - 1] == false) {// 防止重复分析
					v[x - 1] = true;

					if (a[x - 1] == true) {
						res = i + 1;
					} else {
						for (int j = 0; j < n; j++) {
							a[j] = true;
						}
						a[x - 1] = false;
						k = n - 1;
					}

				}

			}
		}

		return res;
	}

	public static void main(String[] args) {
		int n;
		Scanner sc = new Scanner(System.in);
		n = sc.nextInt();
		for (int i = 0; i < n; i++) {
			int res = fun(sc);
			System.out.println(res);
		}
		sc.close();
	}

}