|amount|[long](../types/long.md) | Yes|Price of the product in the smallest units of the currency (integer, not float/double). For example, for a price of `US$ 1.45` pass `amount = 145`. See the exp parameter in [currencies.json](https://core.telegram.org/bots/payments/currencies.json), it shows the number of digits past the decimal point for each currency (2 for the majority of currencies).|