5 3
 1000 3
 777 17
 4 3
 2 2
 100 4
 10 4
 999 2
 6 4
 1 2
 17 3
 1 4
 26 8
 91 5
 1 3
 1000 2
 20 3
 9 4
 123 5
 1000 1000
 3 2
 3 3
 80 970
 1000 4
 1 1000

7
 1499
 825
 5
 3
 133
 13
 1997
 7
 1
 25
 1
 29
 113
 1
 1999
 29
 11
 153
 1001
 5
 4
 80
 1333
 1

from collections import Counter
n, k = list(map(lambda x: int(x),input().split()))
first_line = n
cnt, iteration = first_line, 0
while(n>1):
    if iteration!=0 and int(n/k)>k:
        cnt+= n+(n%k)
    else: 
        cnt+= int(n/k)
        
    n= int(n/k)   
    iteration+=1
print(cnt)

