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

import sys
(a,b) = sys.stdin.readline().strip().split(' ')
(a,b) = (int(a),int(b))

def foo(a,b):
    r = 0
    left = 0
    while a:
        r += a
        left += a % b
        a = a / b
    return (r,left)

answer = 0
q = foo(a,b)
while q[0]:
    answer += q[0]
    q = foo(q[1] / b, b)
print answer
