q = 10^9

comb n r = iterate (scanl1 (\x y -> mod (x+y) q)) [1,1..] !! (n'-r') !! r'
 where [n',r'] = map fromIntegral [n,r]

main = getContents >>= print . otoshidama . map read . words

otoshidama :: [Integer] -> Integer
otoshidama [n,m] = let r = mod n (1000*m) in mod (comb m (div r 1000)) q