Check multiple data in drop down in website

I want to check multiple checkboxes in the dropdown in web automation. but select item and select multiple item activity are not I need to check multiple data when I select 1 checkbox for example selector is idx=800 so there are almost 200 checkboxes in the dropdown so first IDX is 800 and the last is IDX 1000 so how to check multiple checkbox using activities. In my excel multiple cities, I have to check for example delhi, Mumbai, Agra, Pune … its better someone provides some demo project it really helps me a lot.


Can you provide the site where you have some many fields?
Or a screenshot?

How the selector appears?


In selector idx change for 1st checkbox it is 800 and last checkbox idx is 1000… Like every next checkbox idx value is increment by 1…