#include <iostream>

using namespace std;

int main ()
{
	int n,x,y, s=0;
	int c;
	cin >> n;
	int a[100][2] = {0};
	for (int i=1; i<2*n; i+=2)
	{
		cout <<i<<" "<<i+1<<endl;
		if (!(cin >> x))
		{
			s+=1;
			cin.clear();
			cin.ignore(10, '\n');
		}
		else
		{
			if (x == -1) {return 0;}
			cin >> y;
			if (a[x][0] == 0) a[x][0] = i;
			else a[x][1] = i;
			if (a[y][0] == 0) a[y][0] = i+1;
			else a[y][1] = i+1;
		}
	}
	for (int i=1; i<=n-s; i++)
	{
		if (a[i][0] != 0)
		{cout << a[i][0] <<" " << a[i][1]<<endl;}
		if (!(cin >> c))
		{
			cin.clear();
			cin.ignore(10, '\n');
		}
		else return 0;
	}
	cout << -1;
	return 0;
}