Schedule of Basic and Diluted Earnings per Share (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Income Per Share of Common Stock
Net income	$ 161,000	$ 4,447,000	$ 3,595,000	$ 7,799,000
Basic EPS, Income	$ 161,000	$ 4,447,000	$ 3,595,000	$ 7,799,000
Basic EPS, Shares	4,943,985	4,948,224	4,945,192	4,949,351
Basic EPS, Per-share	$ 0.03	$ 0.90	$ 0.73	$ 1.58
Effect of dilutive Convertible Preferred Stock, Income
Effect of dilutive Convertible Preferred Stock, Shares	20,500	20,500	20,500	20,500
Effect of dilutive Convertible Preferred Stock, Per-share
Diluted EPS, Income	$ 161,000	$ 4,447,000	$ 3,595,000	$ 7,799,000
Diluted EPS, Shares	4,964,485	4,968,724	4,965,692	4,969,851
Diluted EPS, Per-share	$ 0.03	$ 0.89	$ 0.72	$ 1.57