#!/usr/bin/env python3
n = int(input())
a, b, c, d = map(int, input().split())
l = [(a, b), (c, d)]
for _ in range(n):
    x, y = map(int, input().split())
    l.append((x, y))
if len(set(l)) != n + 2: exit(1)
exit(42)