FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($)	Feb. 28, 2023	May 31, 2022
Money Market Funds [Member]
Investment securities	$ 11,876,000	$ 28,609,000
Level 1 [Member] | Money Market Funds [Member]
Investment securities	11,876,000	28,609,000
Level 1 [Member] | US Treasury Securities [Member]
Investment securities	29,560,000
Level 2 [Member] | Money Market Funds [Member]
Investment securities	0	0
Level 2 [Member] | US Treasury Securities [Member]
Investment securities	0
Level 3 [Member] | Money Market Funds [Member]
Investment securities	0	$ 0
Level 3 [Member] | US Treasury Securities [Member]
Investment securities	0
Assets [Member]
Investment securities	41,436,000
Assets [Member] | Level 1 [Member]
Investment securities	41,436,000
Assets [Member] | Level 2 [Member]
Investment securities	0
Assets [Member] | Level 3 [Member]
Investment securities	0
U.S. treasury securities [Member]
Investment securities	$ 29,560,000