Summary of significant accounting policies (Details)	Dec. 31, 2023	Dec. 31, 2022
Period End [Member] | China, Yuan Renminbi
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.10700	6.96310
Period End [Member] | Hong Kong, Dollars
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.81005	7.81325
Average [Member] | China, Yuan Renminbi
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.07165
Average [Member] | Hong Kong, Dollars
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.82918