def workbook(n, k, arr):
    # Write your code here
  
    ch = []
    
    # step 1: create chapters
    for i in arr:
        c = list(range(1,i+1))
        for j in range(1,i//k+1):
            ch.append(c[:k])
            c = c[k:] # this might add some empty chapters
        ch.append(c)
        
    ch = list(filter(lambda i: len(i) != 0, ch)) # remove empty chapters

    #step 2: find special problems
    count = 0
    for i,j in enumerate(ch):
        if i + 1 in j:
            count +=1
        
    return count