Q = int(input())
for i in range(Q):
  A,B,C = [int(x) for x in input().split()]
  ans = 0
  if C==1:
    print(-1)
    continue
  if A<C:
    print(B)
    continue
  while A>C:
    #print(A)
    if A<=2*(C-1):
      ans+=2
      A=1
      break
    if A%C!=0:
      A = A-A%C
      ans+=1
    if A==C:
      ans+=2
      A=1
      break
    A = A/C
    ans+=1
  if A==C:
    ans+=2
  elif A!=1:
    ans+=1
  print(ans*B)