Summary of significant accounting policies (Details 1)	6 Months Ended
Jun. 30, 2025 USD ($)	Jun. 30, 2025 CNY (¥)	Jun. 30, 2024 CNY (¥)
Product Information [Line Items]
Total revenues	$ 26,277,782	¥ 188,112,127	¥ 290,441,871
Central Processing Advertising Algorithm Services [Member]
Product Information [Line Items]
Total revenues	$ 26,277,782	¥ 188,112,127	¥ 290,441,871

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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+ Details