#yuki915

q=int(raw_input())
for i in range(q):
 a,b,c=map(int,raw_input().split())
 if c==1:
  print -1
  continue
 cnt=0
 while a>(c-1)*2:
  if a%c==0:
   a/=c
   cnt+=1
  else:
   a=a/c*c
   cnt+=1
 if a<c:
  cnt+=1
 else:
  cnt+=2
 print cnt*b