import Data.Functor
import Control.Monad

toTuple :: [Int] -> (Int, Int)
toTuple [x, y] = (x, y)

readPoint :: IO (Int, Int)
readPoint = toTuple . map read . words <$> getLine

solveOne :: IO ()
solveOne = do
    n <- readLn :: IO Int
    points <- replicateM n readPoint
    let xs = map fst points
        ys = map snd points
        maxX = maximum xs
        minX = minimum xs
        maxY = maximum ys
        minY = minimum ys
        onEdge (x, y)
            | (x == maxX || x == minX) && y >= minY && y <= maxY = True
            | (y == maxY || y == minY) && x >= minX && x <= maxX = True
            | otherwise = False
            
        allOnEdge = all onEdge points
        
    putStrLn $ if allOnEdge then "YES" else "NO"
    
main = do
    q <- readLn :: IO Int
    replicateM q solveOne