import java.util.ArrayList;
import java.util.Scanner;

public class Interactive {

	public static void main(String[] args) {

		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int i1, i2, mosse = 2*n;
		int numMatch = 0;

		for (int i = 0; i < mosse; i++) {
			if(numMatch==n) {
				System.out.printf("-1");
				System.out.flush();
				return;
			}
			for (int j = i+1; j < mosse; j++) {
				System.out.printf("%d %d", i+1, j+1);
				System.out.flush();
				String lettura = in.next();
				if(lettura.equalsIgnoreCase("MATCH")) {
					numMatch++;
					break;
				} else if(lettura.equalsIgnoreCase("-1")) return;
			}
		}
	}
}