Note I - Stock-based Compensation (Tables)

3 Months Ended

Jul. 31, 2018

Notes Tables

Stock Option Plan Comparison [Table Text Block]

	Restated Option Plan
Minimum exercise price as a percentage of fair market value at date of grant	100%
Last expiration date for outstanding options	May 8, 2028
Shares available for grant at July 31, 2018	98,500

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended July 31,
	2018			2017
Expected term (years)		5.5			5.5
Risk-free interest rate		2.78	%		1.81	%
Volatility		36	%		36	%
Dividend yield		-			-

Schedule of Share-based Compensation, Stock Options, Exercises [Table Text Block]

	Three Months Ended July 31,
(Dollars in thousands)	2018		2017
Options exercised		162,250		35,250
Cash received from option exercises	$	3,259	$	543
Intrinsic value of options exercised	$	5,508	$	784