![](https://cos-cdn.shuashuati.com/pipixue-web/2020-1231-2005-12/ti_inject-812ce.png)
The figure given below shows the market for shoes in the U.S. The domestic price line with tariff lies above the international price line. D d and S d are the domestic demand and supply curves of shoes respectively. The production effect of the tariff on shoes is measured by the area _____.