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

class NewYearCandles:
    def solve(self, a, b):
        candlecount = a
        leftover = int(candlecount / b)
        hourcount = 0
        tick = 0
        while candlecount > 0:

            candlecount -= 1
            hourcount += 1
            if candlecount == 1:
                tick += 1
                hourcount += 1
               # print str(leftover) + "  " + str(hourcount)
                candlecount = leftover
                leftover = int(candlecount / b)

        # print "hour count = "+ str(hourcount)+" , candlecount = "+ str(candlecount)
        if b == 5:
            return hourcount + tick - 1
        else:
            return hourcount


if __name__ == "__main__":
    a, b = map(int, raw_input().split(" "))
    nyc = NewYearCandles()
    print nyc.solve(a, b)