Use CSV count occurrences to populate value instead of updating each time

Question

I would like to set the number of occurrences of the count(Category) to automatically replace the 155. The df is continually expanding and want my code to read the number of occurrences (which it is doing) then output so I do not have to manually change the 155.

df %>% 
  filter(dfCategory !='N/A', !is.na(dfCategory)) %>%  #filter your data
  count(Category)

#cat is

cat <- isolate(input$selectCategory)

Grant is one of the different values in the Category column of my df

if(cat == 'Grant'){
 holidays <- head(coorespondingCSV, 155 + hrzn)
 }