main = do
 [_,l] <- map read . words <$> getLine
 xwts <- map (map read . words) . lines <$> getContents
 print (crossing l xwts)

crossing :: Int -> [[Int]] -> Int
crossing l = rest . foldl cross (0,0)
 where
  rest (t,d) = t + (l-d)
  cross (t',d') xwt@[x,w,t]
   | d' /= x = cross (t'+(x-d'),x) xwt
   | mod t' (2*t) >= t = cross (next,d') xwt
   | t - mod t' (2*t) < w = cross (next,d') xwt
   | otherwise = (t'+w,d'+w)
   where next = head (dropWhile (<t') (iterate (+ (2*t)) 0))