백준 1673 치킨 쿠폰

n = []
k = []
while True:
try:
line = input()
except EOFError:
break
a, b = line.split(" ")
n.append(int(a))
k.append(int(b))

cnt_array = []

for i in range(len(n)):
nc = n[i] #now coupon
need = k[i] #need dozang
cnt = nc
while((nc - need) >= 0):
nc = nc - need + 1
cnt += 1
cnt_array.append(cnt)

for j in range(len(cnt_array)):
print(cnt_array[j])