Annual report pursuant to Section 13 and 15(d)

STOCKHOLDERS' EQUITY (Details) - Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range

v3.21.2
STOCKHOLDERS' EQUITY (Details) - Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range - $ / shares
 12 Months Ended
May 31, 2019
May 31, 2021
May 31, 2020
Apr. 15, 2021
Jul. 19, 2019
Jul. 08, 2019
May 30, 2019
Jun. 20, 2018
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]                
Exercise Price       $ 0.40 $ 1.10 $ 1.10   $ 0.45
Number of warrants outstanding (in Shares)   53,997,645 54,835,145       54,818,985  
Weighted average remaining contractual life   186 days            
Weighted average exercise price of outstanding warrants $ 0.53 $ 0.53 $ 0.53          
Number of warrants exercisable (in Shares)   53,997,645            
Weighted average exercise price of exercisable warrants   $ 0.53            
Warrant Exercisable at $0.49 [Member]                
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]                
Exercise Price   $ 0.49            
Number of warrants outstanding (in Shares)   33,465,110            
Weighted average remaining contractual life   1 year 6 months            
Weighted average exercise price of outstanding warrants   $ 0.49            
Number of warrants exercisable (in Shares)   33,465,110            
Weighted average exercise price of exercisable warrants   $ 0.49            
Warrants Exercisable at $0.50 [Member]                
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]                
Exercise Price   $ 0.50            
Number of warrants outstanding (in Shares)   2,736,500            
Weighted average remaining contractual life   1 year 266 days            
Weighted average exercise price of outstanding warrants   $ 0.50            
Number of warrants exercisable (in Shares)   2,736,500            
Weighted average exercise price of exercisable warrants   $ 0.50            
Warrant Exercisable at $0.60 [Member]                
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]                
Exercise Price   $ 0.60            
Number of warrants outstanding (in Shares)   17,500,000            
Weighted average remaining contractual life   1 year 6 months            
Weighted average exercise price of outstanding warrants   $ 0.60            
Number of warrants exercisable (in Shares)   17,500,000            
Weighted average exercise price of exercisable warrants   $ 0.60            
Warrant Exercisable at $1.10 [Member]                
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]                
Exercise Price   $ 1.10            
Number of warrants outstanding (in Shares)   296,035            
Weighted average remaining contractual life   1 year 204 days            
Weighted average exercise price of outstanding warrants   $ 1.10            
Number of warrants exercisable (in Shares)   296,035            
Weighted average exercise price of exercisable warrants   $ 1.10