diff --git a/app/Main.hs b/app/Main.hs
index 65ae4a0..f3b2830 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -1,4 +1,8 @@
 module Main where
 
+import qualified Lexer
+
 main :: IO ()
-main = putStrLn "Hello, Haskell!"
+main = do
+  source <- readFile "arithmetic.txt"
+  putStr $ show (Lexer.lex source)
diff --git a/arithmetic.txt b/arithmetic.txt
new file mode 100644
index 0000000..9e02457
--- /dev/null
+++ b/arithmetic.txt
@@ -0,0 +1 @@
+1 + 22 * (3 - 4)
\ No newline at end of file