{-# OPTIONS_GHC -O2 #-}
{-# LANGUAGE BangPatterns, CPP, FlexibleContexts, FlexibleInstances, GADTs  #-}
{-# LANGUAGE KindSignatures, LambdaCase, MagicHash, MultiParamTypeClasses   #-}
{-# LANGUAGE MultiWayIf, OverloadedStrings, RecordWildCards                 #-}
{-# LANGUAGE ScopedTypeVariables, TupleSections, TypeFamilies, ViewPatterns #-}

import           Control.Applicative
import           Control.Exception
import           Control.Monad
import           Control.Monad.Primitive
import           Control.Monad.ST
import           Control.Monad.State.Strict
import           Data.Bool
import qualified Data.ByteString             as B
import qualified Data.ByteString.Builder     as B
import qualified Data.ByteString.Char8       as C
import qualified Data.ByteString.Internal    as B
import qualified Data.ByteString.Unsafe      as B
import           Data.Char
import qualified Data.Foldable               as F
import           Data.Function
import           Data.Functor.Identity
import qualified Data.IntMap.Strict          as IM
import qualified Data.IntSet                 as IS
import qualified Data.List                   as L
import qualified Data.Map.Strict             as M
import           Data.Monoid
import           Data.Ord
import           Data.Primitive.MutVar
import           Data.Ratio
import qualified Data.Set                    as S
import           Data.Tuple
import qualified Data.Vector                 as V
import qualified Data.Vector.Generic         as G
import qualified Data.Vector.Generic.Mutable as GM
import qualified Data.Vector.Mutable         as VM
import qualified Data.Vector.Unboxed         as U
import qualified Data.Vector.Unboxed.Mutable as UM
import           Debug.Trace
import           Foreign                     hiding (void)
import           GHC.Exts
import qualified System.IO                   as IO
import           Unsafe.Coerce

main :: IO ()
main = do
    [n, t] <- map read.words <$> getLine :: IO [Int]
    xs <- U.unfoldrN n (runParser $ (,) <$> int <*> int) <$> C.getContents
    print $ solve n t xs

ix :: Int -> Int -> Int
ix i j = i * 4096 + j
{-# INLINE ix #-}

solve :: Int -> Int -> U.Vector (Int, Int) -> Int
solve n t (L.sort.U.toList -> xs) = runST $ do
    dp <- UM.replicate (4096 * 4096) 0
    forM_ (zip[0..]xs) $ \(i, (a, b)) -> do
        UM.unsafeCopy
            (UM.slice (ix (i+1) 0) (t+1) dp)
            (UM.slice (ix i 0) (t+1) dp)
        rep t $ \j -> do
            !w <- (+b) <$> UM.read dp (ix i j)
            UM.modify dp (max w) (ix (i + 1) (min t $ j + a))
    U.maximum <$> U.unsafeFreeze (UM.slice (ix n 0) (t + 1) dp)


-------------------------------------------------------------------------------
-- Utils
-------------------------------------------------------------------------------
rep :: Monad m => Int -> (Int -> m ()) -> m ()
rep !n = U.forM_ $ U.generate n id
{-# INLINE rep #-}
rev :: Monad m => Int -> (Int -> m ()) -> m ()
rev !n = U.forM_ $ U.iterateN n (subtract 1) (n - 1)
{-# INLINE rev #-}
infixl 8 `shiftRL`, `unsafeShiftRL`
shiftRL = unsafeShiftRL
{-# INLINE shiftRL #-}
unsafeShiftRL (I# x#) (I# i#) = I# (uncheckedIShiftRL# x# i#)
{-# INLINE unsafeShiftRL #-}
type Parser a = StateT C.ByteString Maybe a
runParser :: Parser a -> C.ByteString -> Maybe (a, C.ByteString)
runParser = runStateT
{-# INLINE runParser #-}
int :: Parser Int
int = coerce $ C.readInt . C.dropWhile isSpace
{-# INLINE int #-}
int1 :: Parser Int
int1 = fmap (subtract 1) int
{-# INLINE int1 #-}
char :: Parser Char
char = coerce C.uncons
{-# INLINE char #-}
byte :: Parser Word8
byte = coerce B.uncons
{-# INLINE byte #-}

Measured memory_bytes: 134780