diff --git a/ChangeLog.md b/ChangeLog.md
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--- /dev/null
+++ b/ChangeLog.md
@@ -0,0 +1,3 @@
+# Changelog for homura-stopwatch
+
+## Unreleased changes
diff --git a/LICENSE b/LICENSE
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--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License Copyright (c) 2020 ncaq
+
+Permission is hereby granted, free of
+charge, to any person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the Software without
+restriction, including without limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to the
+following conditions:
+
+The above copyright notice and this permission notice
+(including the next paragraph) shall be included in all copies or substantial
+portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
+EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/README.md b/README.md
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--- /dev/null
+++ b/README.md
@@ -0,0 +1,35 @@
+# homura-stopwatch
+
+input
+
+~~~shell
+echo "
+10:30 10:40 tvirus
+10:40 12:28 icbm
+12:28 14:59 gsomia
+15:41 15:57 gsomia
+15:57 16:35 panzer
+16:35 17:17 icbm
+17:17 17:28 gsomia
+17:28 18:15 icbm
+18:15 18:42 gsomia
+18:42 19:44 icbm
+19:44 20:04 gsomia
+20:04 21:10 icbm
+22:10 23:27 icbm" | homura-stopwatch
+~~~
+
+output
+
+~~~shell
+tvirus	0:10
+icbm	6:42
+gsomia	3:45
+panzer	0:38
+~~~
+
+区切りは`\n`でも`,`でもOKです.
+
+~~~shell
+echo "10:30 10:40 tvirus, 10:40 12:28 icbm, 12:28 14:59 gsomia, 15:41 15:57 gsomia, 15:57 16:35 panzer, 16:35 17:17 icbm, 17:17 17:28 gsomia, 17:28 18:15 icbm, 18:15 18:42 gsomia, 18:42 19:44 icbm, 19:44 20:04 gsomia, 20:04 21:10 icbm, 22:10 23:27 icbm" | homura-stopwatch
+~~~
diff --git a/Setup.hs b/Setup.hs
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--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/app/Main.hs b/app/Main.hs
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--- /dev/null
+++ b/app/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import           Lib (appMain)
+
+main :: IO ()
+main = appMain
diff --git a/homura-stopwatch.cabal b/homura-stopwatch.cabal
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--- /dev/null
+++ b/homura-stopwatch.cabal
@@ -0,0 +1,54 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.31.2.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: 3be341d8b5700047d9fa3c6406ff3e05ff4e7f275daf4fab10484f878e52000f
+
+name:           homura-stopwatch
+version:        0.1.3
+description:    Please see the README on GitHub at <https://github.com/ncaq/homura-stopwatch#readme>
+homepage:       https://github.com/ncaq/homura-stopwatch#readme
+bug-reports:    https://github.com/ncaq/homura-stopwatch/issues
+author:         ncaq
+maintainer:     ncaq@ncaq.net
+copyright:      © ncaq
+license:        MIT
+license-file:   LICENSE
+build-type:     Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+source-repository head
+  type: git
+  location: https://github.com/ncaq/homura-stopwatch
+
+library
+  exposed-modules:
+      Lib
+  other-modules:
+      Paths_homura_stopwatch
+  hs-source-dirs:
+      src
+  ghc-options: -Wall -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-exported-signatures -Wmissing-home-modules -Wredundant-constraints -Wcompat
+  build-depends:
+      base >=4.7 && <5
+    , hourglass
+    , split
+  default-language: Haskell2010
+
+executable homura-stopwatch
+  main-is: Main.hs
+  other-modules:
+      Paths_homura_stopwatch
+  hs-source-dirs:
+      app
+  ghc-options: -Wall -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-exported-signatures -Wmissing-home-modules -Wredundant-constraints -Wcompat -O2 -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      base >=4.7 && <5
+    , homura-stopwatch
+    , hourglass
+    , split
+  default-language: Haskell2010
diff --git a/src/Lib.hs b/src/Lib.hs
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--- /dev/null
+++ b/src/Lib.hs
@@ -0,0 +1,61 @@
+{-# LANGUAGE LambdaCase #-}
+module Lib ( appMain ) where
+
+import           Data.Hourglass
+import           Data.List
+import           Data.List.Split
+import           Text.Read
+import           Time.System
+
+data Work
+  = Work
+  { workName :: String -- ^ この程度の効率を気にしないプログラムでTextを持ち出すのは面倒になった
+  , workTime :: Seconds
+  }
+  deriving (Eq, Ord, Read, Show)
+
+appMain :: IO ()
+appMain = do
+  contents <- getContents
+  date <- dtDate <$> dateCurrent
+  works <- mapM (\case Left msg -> fail msg -- もうちょい綺麗に書けないかな, fromRightは何故かダメでした…
+                       Right work -> pure work
+                ) $ parseWork date <$> wordsBy (\c -> c == ',' || c == '\n') contents
+  putStr $ workgroupPrettyStr $ collectWorkGroup works
+
+parseWork :: Date -> String -> Either String Work
+parseWork date str
+  = case words str of
+      startStr : endStr : tl ->
+        let parse source = case splitOn ":" source of
+              [hs, ss] -> do
+                h <- readMaybe hs
+                s <- readMaybe ss
+                pure $ DateTime date $ TimeOfDay{todHour = Hours h, todMin = Minutes s, todSec = 0, todNSec = 0}
+              _ -> Nothing
+            leftParse s =  Left $ "次の時刻表記が認識できませんでした: " <> s
+        in case (parse startStr, parse endStr) of
+          (Just workStart, Just workEnd) -> Right $ Work{workName = concat tl, workTime = workEnd `timeDiff` workStart}
+          (Nothing, Just _) -> leftParse startStr
+          (Just _, Nothing) -> leftParse endStr
+          (Nothing, Nothing) -> leftParse $ startStr <> " && " <> endStr
+      _ -> Left $ "文字列を認識できませんでした: " <> str
+
+collectWorkGroup :: [Work] -> [Work]
+collectWorkGroup = foldr addWork []
+
+addWork :: Work -> [Work] -> [Work]
+addWork work works = case find (\w -> workName w == workName work) works of
+  Nothing -> work : works
+  Just progressWork
+    -> Work{workName = workName work, workTime = workTime progressWork + workTime work} :
+       progressWork `delete` works
+
+workgroupPrettyStr :: [Work] -> String
+workgroupPrettyStr works = unlines (workPrettyStr <$> works)
+
+workPrettyStr :: Work -> String
+workPrettyStr work
+  = case fromSeconds (workTime work) of
+      (d, 0) -> workName work <> "\t" <> show (toInteger $ durationHours d) <> ":" <> show (toInteger $ durationMinutes d)
+      o -> error $ "出力がヘンになりました: " <> show o