I am trying to fetch codeforces problems filtered by difficulty tags.

The docs https://codeforces.com/apiHelp/methods#problemset.problems say the problems can be filtered by tags but when I tried the following two urls, I didn't get any response from the API.

• https://codeforces.com/api/problemset.problems?tags=1800-1800
• https://codeforces.com/api/problemset.problems?tags=*1800-*1800

What can I do here?