Summary of significant accounting policies (Details 1)	6 Months Ended
Jun. 30, 2026 USD ($)	Jun. 30, 2026 CNY (¥)	Jun. 30, 2025 CNY (¥)
Product Information [Line Items]
Total revenues	$ 20,071,752	¥ 136,706,698	¥ 188,112,127
Central Processing Advertising Algorithm Services [Member]
Product Information [Line Items]
Total revenues	$ 20,071,752	¥ 136,706,698	¥ 188,112,127

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