353. Lockdown in Mirzapur
Due to the nationwide lockdown caused by COVID-19, Guddu Bhaiya and Bablu Bhaiya in Mirzapur are confined to their homes. They are looking for ways to keep themselves occupied and have come up with a list of activities they can do at home. However, they can only do a limited number of activities each day.
They want to know how many different combinations of activities they can choose to do on any given day. They need your help to calculate this.
Each subsequent line contains two integers N and R, representing the total number of activities and the number of activities they can do in a day, respectively.
1 <= R <= N <= 20