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

"""
Problem: Codeforces Goodbye 2013 Contest Problem A

Author          : chaotic_iak (http://chaoticiak.comlu.com/)
Language        : Python 2.7
Released under  : CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/)
Template version: 20131230
"""

def main():
    a,b = [int(x) for x in get(0)]
    res = 0
    while a >= b:
        a -= b-1
        res += b
    res += a
    print res

############################# NON-IMPORTANT STUFF #############################
# To handle input, including automatic breaking at whitespace. To shoo away
# some stupid hacks regarding whitespaces, since I don't know the validator.
class InputHandler(object):
    s = ""
    
    def get(self, num = 1):
        
        if num > 1:     # Quick way to get a list of num elements
            res = []
            for i in range(num):
                res.append(self.get())
            return res
        
        try:
            if self.s == "": self.s = raw_input()
        except:
            pass
        
        if num == 1:    # Return a string until the next whitespace
            l = self.s.split(None, 1)
            self.s = "" if len(l) == 1 else l[1]
            return l[0]
        
        if num == 0:    # Return as a list, breaking at whitespace
            x, self.s = self.s.split(), ""
            return x
        
        if num == -1:   # Return as a string, keeping whitespace
            x, self.s = self.s, ""
            return x

ih = InputHandler()
get = ih.get
main()