main = interact countTripleDepths

countDepths :: String -> String
countDepths depths =
  let parse x = map (read) (lines x)
  in
    show (depthCounter (parse depths)) ++ "\n"

slide :: Int -> [a] -> [[a]]
slide _ [] = []
slide len list = (take len list):(slide len xs)
  where (x:xs) = list

countTripleDepths :: String -> String
countTripleDepths depths =
  let
    parse x = map (read) (lines x)
    deNoise x = map (sum) (slide 3 x)
  in
    show (depthCounter (deNoise (parse depths))) ++ "\n"

depthCounter :: (Integral a) => [a] -> a
depthCounter [] = 0
depthCounter [_] = 0
depthCounter (x:xs) = if x < head xs
                    then 1 + depthCounter xs
                    else 0 + depthCounter xs