#!/bin/ruby

n = gets.strip.to_i
min = -100
i = j = min
onX = onY = true
n.times do
    x, y = gets.strip.split(' ').map(&:to_i)
    onX = false if (i > min && x != i)
    onY = false if (j > min && y != j)
    i = x
    j = y
end
if onX || onY
    puts "YES"
else
    puts "NO"
end