Balance Sheets (Parenthetical) - USD ($)	Apr. 30, 2024	Apr. 30, 2023
Trade, allowance for credit loss, current	$ 34,256	$ 17,922
Convertible preferred stock, shares authorized	1,000,000	1,000,000
Class A common stock, par value	$ 10	$ 10
Class A common stock, shares authorized	10,000,000	10,000,000
Class A common stock, shares issued	8,502,881	8,502,881
Class A common stock, shares outstanding	8,502,881	8,502,881
Treasury stock, shares	3,606,151	3,572,338
Noncumulative Preferred Stock [Member]
Convertible preferred stock, shares authorized	25,000	25,000
Convertible preferred stock, stated value	$ 20	$ 20
Convertible preferred stock, shares issued	4,100	4,100
Convertible preferred stock, shares outstanding	4,100	4,100