package main

import "fmt"
import "reflect"

func log(items... interface{}) {
	fmt.Println(items...)
}

func bug(items... interface{}) {
	panic("bug " + fmt.Sprint(items...))
}

func assert(condition bool, items... interface{}) {
	if !condition {
		panic("assertion failed: " + fmt.Sprint(items...))
	}
}

func scanln(args... interface{}) {
	nargs := make([]interface{}, 0, len(args))
	for _, arg := range args {
		switch reflect.TypeOf(arg).Kind() {
		case reflect.Slice:
			v := reflect.ValueOf(arg)
			n := v.Len()
			for i := 0; i < n; i++ {
				nargs = append(nargs, v.Index(i).Addr().Interface())
			}
		default:
			nargs = append(nargs, arg)
		}
	}
	n, e := fmt.Scanln(nargs...)
	if e != nil {
		panic(e)
	}
	assert(n == len(nargs))
}

func check(n, low, high int) {
	if n < low || n > high {
		bug("bad input: ", n, " not in range ", low, " to ", high)
	}
}

func main() {
	var N int
	scanln(&N)
	check(N, 2, 10)
	var x0, y0 int
	scanln(&x0, &y0)
	vert := true
	hor := true
	for n := 1; n < N; n++ {
		var x, y int
		scanln(&x, &y)
		if x != x0 {
			vert = false
		}
		if y != y0 {
			hor = false
		}
	}
	if vert || hor {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}