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Summary of significant accounting policies (Details)
12 Months Ended
Dec. 31, 2021
Office equipment and furniture [Member]  
Statement [Line Items]  
Estimated Useful Life 3-5 years
Vehicles [Member]  
Statement [Line Items]  
Estimated Useful Life 5 years
Leasehold improvements [Member]  
Statement [Line Items]  
Estimated Useful Life 5 years
Property [Member]  
Statement [Line Items]  
Estimated Useful Life 20 years