import Control.Applicative
import Control.Monad
import Control.Monad.ST
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.IArray
--import Data.Array.Unboxed
import Data.Array.MArray
import Data.Array.IO
import Data.Array.ST
import Data.IORef
import Data.STRef
-- import System.IO.Unsafe
 
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
sjoin :: (Show a) => [a] -> String
sjoin = unwords . map show
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
fnBin :: (b -> c -> d) -> (a -> b) -> (a -> c) -> a -> d
fnBin op f g x = op (f x) $ g x
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)
modifyArray :: (Ix i, MArray a e m) => a i e -> i -> (e -> e) -> m ()
modifyArray arr ix f = readArray arr ix >>= writeArray arr ix . f
dictCompare :: [a -> a -> Ordering] -> a -> a -> Ordering
dictCompare [] _ _ = EQ
dictCompare (f:fs) x y = let c = f x y in if c==EQ then dictCompare fs x y else c
-- end of templete



main = do
    [n, m] <- getInts
    list <- zip [1..] <$> replicateM n getInt
    bs <- replicateM m getInt
    print . head . maximumBy (comparing length) . group . sort $ [fst $ head $ filter ((<=b) . snd) list | b <- bs]
