#include <algorithm>
#include <cassert>
#include <iostream>
#include <vector>
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using namespace std;

int main() {

  int n;
  cin >> n;
  assert(1 <= n and n <= 2000);
  rep(i, n) {
    int a, b;
    cin >> a >> b;
    assert(1 <= a and a <= 100000);
    assert(1 <= b and b <= 100000);
  }
  cout << -1 << endl;
  
  return 0;
}