diff --git a/ft_putchar.c b/ft_putchar.c
index 16f7bf8..de49b7c 100644
--- a/ft_putchar.c
+++ b/ft_putchar.c
@@ -6,12 +6,13 @@
 /*   By: jtorrez- <marvin@42.fr>                    +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/03/18 20:27:12 by jtorrez-          #+#    #+#             */
-/*   Updated: 2023/03/18 20:27:13 by jtorrez-         ###   ########.fr       */
+/*   Updated: 2023/03/19 04:21:28 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <unistd.h>
 
+// Display an ASCII char on standard output.
 void	ft_putchar(char c)
 {
 	write(1, &c, 1);
diff --git a/main.c b/main.c
index fa55b48..366f400 100644
--- a/main.c
+++ b/main.c
@@ -6,26 +6,50 @@
 /*   By: jtorrez- <marvin@42.fr>                    +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/03/18 20:15:26 by jtorrez-          #+#    #+#             */
-/*   Updated: 2023/03/18 20:21:42 by jtorrez-         ###   ########.fr       */
+/*   Updated: 2023/03/19 04:22:13 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 void	rush(int x, int y);
 int		ft_atoi(char *str);
+void	ft_putchar(char c);
+void	ft_putstr(char *str);
 
+// entry point of the program
+// Parses the program arguments and fails if the number of passed
+// arguments is not 2.
+// Also fails if the passed arguments are out of
+// bounds (200 for width, 100 for height).
+// argv[0] contains the path of the executable, eg ./rush00
 int	main(int argc, char *argv[])
 {
 	int	width;
 	int	height;
 
 	if (argc != 3)
+	{
+		ft_putstr("Usage: ");
+		ft_putstr(argv[0]);
+		ft_putstr(" [width] [height]\n");
 		return (1);
+	}
 	width = ft_atoi(argv[1]);
 	height = ft_atoi(argv[2]);
+	if (width >= 200)
+	{
+		ft_putstr("Width must be less than 200\n");
+		return (2);
+	}
+	if (height >= 100)
+	{
+		ft_putstr("Height must be less than 100\n");
+		return (3);
+	}
 	rush(width, height);
 	return (0);
 }
 
+// Convert a string to an integer
 int	ft_atoi(char *str)
 {
 	int	i;
@@ -37,3 +61,13 @@ int	ft_atoi(char *str)
 		number = number * 10 + (str[i++] - '0');
 	return (number);
 }
+
+// Display a null-terminated string on standard output.
+void	ft_putstr(char *str)
+{
+	int	i;
+
+	i = 0;
+	while (str[i] != '\0')
+		ft_putchar(str[i++]);
+}
diff --git a/rush00 b/rush00
new file mode 100755
index 0000000..b0d4001
Binary files /dev/null and b/rush00 differ
diff --git a/rush00.c b/rush00.c
index 41b6d2e..bdaedd7 100644
--- a/rush00.c
+++ b/rush00.c
@@ -6,7 +6,7 @@
 /*   By: jtorrez- <marvin@42.fr>                    +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/03/18 20:15:12 by jtorrez-          #+#    #+#             */
-/*   Updated: 2023/03/18 20:26:32 by jtorrez-         ###   ########.fr       */
+/*   Updated: 2023/03/19 04:21:23 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
@@ -20,6 +20,12 @@ const char	g_corners[] = {'o', 'o', 'o', 'o', '\0'};
 const char	g_horizontal = '-';
 const char	g_vertical = '|';
 
+// Display a rectangle on standard output, specified by a width (x),
+// a height (y), a char array (g_corners) that contains the corners
+// in clockwise direction (starting from the top left), a char that
+// contains the horizontal character (g_horizontal), a char that contains
+// the vertical character (g_vertical), and additionally a char that
+// contains the inside ("the filling") character of the rectangle.
 void	rush(int x, int y)
 {
 	int	i;
@@ -34,6 +40,9 @@ void	rush(int x, int y)
 		horiz_line(g_corners[3], g_horizontal, g_corners[2], x);
 }
 
+// Display a horizontal line on standard output, specified by a single
+// left char, (width - 2) middle chars, and a single right char,
+// followed by a newline at the end.
 void	horiz_line(char left, char middle, char right, int width)
 {
 	int	i;