import Control.Applicative
import Control.Monad
import Control.Monad.ST
-- import qualified Data.ByteString as BS
import Data.Functor
import Data.Function
import Data.Monoid
import Data.Maybe
import Data.List
import qualified Data.Foldable as Foldable
import qualified Data.Set as Set
--import qualified Data.Sequence as Sequence
import Data.List.Split
import Data.Bits
import Data.Char
import Data.Ix
import Data.Ratio
import Data.Ord
import Data.Tuple
import Data.Array
--import Data.Array.Unboxed
--import Data.Array.IArray
import Data.Array.MArray
import Data.Array.IO
import Data.Array.ST
import Data.IORef
import Data.STRef
import GHC.ST
-- import System.IO.Unsafe
 
-- templete
readInt = read :: String -> Int
readInteger = read :: String -> Integer
readDouble = read :: String -> Double
getInt = readLn :: IO Int
getInts = map readInt . words <$> getLine
getInteger = readLn :: IO Integer
getIntegers = map readInteger . words <$> getLine
getDouble = readLn :: IO Double
getDoubles = map readDouble . words <$> getLine
sjoin :: (Show a) => [a] -> String
sjoin = unwords . map show
tjoin :: (Show a, Show b) => (a, b) -> String
tjoin (x, y) = show x ++ (' ' : show y)
cond :: a -> a -> Bool -> a
cond t f c = if c then t else f
apply2 :: (a -> a -> b) -> [a] -> b
apply2 f [x,y] = f x y
apply3 :: (a -> a -> a -> b) -> [a] -> b
apply3 f [x,y,z] = f x y z
apply4 :: (a -> a -> a -> a -> b) -> [a] -> b
apply4 f [x,y,z,w] = f x y z w
fnTuple :: (a -> b, a -> c) -> a -> (b, c)
fnTuple (f,g) a = (f a, g a)
replace :: (Eq a) => a -> a -> [a] -> [a]
replace x y = map (\z -> if z==x then y else z)
binMap :: (a -> a -> b) -> [a] -> [b]
binMap f (x:xs@(y:_)) = f x y : binMap f xs
binMap _ _ = []
splitRec :: Int -> [a] -> [[a]]
splitRec _ [] = []
splitRec n xs = let (y,ys) = splitAt n xs in y : splitRec n ys
infixl 7 `divCeil`
divCeil :: Integral a => a -> a -> a
x `divCeil` y = (x+y-1) `div` y
coverC :: Ord a => (a, a) -> a -> Bool
coverC (l,r) x = l<=x && x<=r
coverH :: Ord a => (a, a) -> a -> Bool
coverH (l,r) x = l<=x && x<r
ibsearch :: (Int -> Bool) -> (Int,Int) -> Int
ibsearch f (ok,ng) = if abs (ok-ng) <= 1 then ok else let mid = (ok + ng) `div` 2 in ibsearch f (if f mid then (mid,ng) else (ok,mid))
-- templete

data Visited = Yet | Temp | Perm 

f :: Array Int [Int] -> Bool
f es = runST $ do
    state <- newArray (1,200) Yet :: ST s (STArray s Int Visited)
    fmap (const True) . sequence <$> forM [1..200] (search es state) >>= return . fromMaybe False


search :: Array Int [Int] -> STArray s Int Visited -> Int -> ST s (Maybe ())
search es visited i = do
    s <- readArray visited i
    case s of
        Temp -> return Nothing
        Perm -> return $ Just ()
        Yet -> do
            writeArray visited i Temp
            r <- fmap mconcat . sequence <$> forM (es!i) (search es visited)
            writeArray visited i Perm
            return r

mapEdge x "lock" y = (readInt y + 100, readInt x)
mapEdge x "wait" y = (readInt x, readInt y + 100)

edgeArr es = runSTArray $ do
    arr <- newArray (1,200) [] :: ST s (STArray s Int [Int])
    forM_ es $ \(i,j) -> readArray arr i >>= writeArray arr i . (j:)
    return arr

main = do
    n <- getInt
    rs <- map (apply3 mapEdge . words) <$> replicateM n getLine
    let es = edgeArr rs
    print $ cond 0 1 $ f es



Measured memory_bytes: 4892