diff --git a/src/cli.rs b/src/cli.rs
index c76ab55..8356ce3 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -1,7 +1,33 @@
+macro_rules! options {
+    ($($name:ident $sflag:literal $lflag:literal $hasarg:literal),* $(,)?) => {
+        enum Options {
+            $($name,)*
+        }
+
+        const SHORT_FLAGS: &[&str] = &[
+            $($sflag,)*
+        ];
+
+        const LONG_FLAGS: &[&str] = &[
+            $($lflag,)*
+        ];
+
+        const HAS_ARG: &[bool] = &[
+            $($hasarg,)*
+        ];
+    };
+}
+
+options! {
+    Width "w" "width" true,
+    Height "h" "height" true,
+}
+
 #[derive(Default)]
 pub struct Cli {
     width: Option<usize>,
     height: Option<usize>,
+    input_file: String,
 }
 
 impl Cli {
@@ -10,6 +36,22 @@ impl Cli {
     }
 
     pub fn run(&mut self) -> Option<()> {
+        let mut args = std::env::args();
+        /* Skip program name. */
+        args.next();
+        loop {
+            if let Some(arg) = args.next() {
+                if arg.starts_with("--") {
+                    let flag = &arg[2..];
+                } else if arg.starts_with("-") {
+                    let flag = &arg[1..2];
+                } else {
+                    self.input_file = arg;
+                }
+            } else {
+                break;
+            }
+        }
         Some(())
     }
 }