package main
import "fmt"

func main() {
    var t int
    var x, xinit, y, yinit int
    var ans string
    
    fmt.Scan(&t)
    for i := 0; i < t; i++ {
        ans = "YES"
        fmt.Scanf("%d %d", &x, &y)
        if i == 0 {
            xinit = x
            yinit = y
        } else {
            if x != xinit && y != yinit {
                ans = "NO"  
                break
            }
        }
    }
    fmt.Print(ans)
}