import System.IO

isOdd :: Integer -> Integer -> Integer
isOdd x y =
 if x > y then 0
 else if mod x 2 /= 0 && mod y 2 /= 0 then ((x + y) `div` 2) * ( (y - x + 2) `div` 2) -- if both numbers are odd
 else if mod x 2 == 0 && mod y 2 == 0 then (((x + y) `div` 2) * (((y - 1) - (x + 1) + 2) `div` 2)) -- if both numbers are even
 else if mod x 2 /= 0 && mod y 2 == 0 then (((x + y - 1) `div` 2) * (((y - 1) - x + 2) `div` 2)) -- if x is odd
 else if mod x 2 == 0 && mod y 2 /= 0 then (((x + 1 + y) `div` 2) * ((y - (x + 1) + 2) `div` 2)) -- if y is odd
 else 0

resultFunction cases 0 = putStrLn "Program ended"

resultFunction cases c = do
  let i = show cases

  putStrLn "write x:"
  x <- readLn :: IO Integer
  putStrLn "write y:"
  y <- readLn :: IO Integer
  putStrLn ("Case " ++ i ++ ":")
  print (isOdd x y)
  resultFunction (cases+1) (c - 1)

main = do
   input1 <- getLine
   let cases = 1
   let input1Number = (read input1 :: Integer)
   resultFunction cases input1Number