import Control.Applicative
import Control.Monad
import System.IO

data Point = Point { getX :: Int,
                     getY :: Int }
           deriving (Eq, Show)

main :: IO ()
main = do
  n_temp <- getLine
  let n = read n_temp :: Int
  arr_temp <- getMultipleLines n
  let listOfPoints = map strToPoint arr_temp
      xCoordinates = map (getX) listOfPoints
      yCoordinates = map (getY) listOfPoints
      answer = if allEquals xCoordinates || allEquals yCoordinates
               then "YES"
               else "NO"
  putStrLn answer

strToPoint :: String -> Point
strToPoint str =
  let (x:y:[]) = words str
  in Point (read x) (read y)

allEquals [] = True
allEquals [_] = True
allEquals (x:y:ys) = if x == y
                     then allEquals (y:ys)
                     else False

getMultipleLines :: Int -> IO [String]
getMultipleLines n
  | n <= 0 = return []
  | otherwise = do          
      x <- getLine         
      xs <- getMultipleLines (n-1)    
      let ret = (x:xs)    
      return ret