import times, strutils, sequtils, math, algorithm, tables, sets, lists, intsets
import critbits, future, strformat, deques
template `max=`(x,y) = x = max(x,y)
template `min=`(x,y) = x = min(x,y)
template `mod=`(x,y) = x = x mod y
template scan2 = (scan(), scan())
template scan3 = (scan(), scan())
let read* = iterator: string {.closure.} =
    while true: (for s in stdin.readLine.split: yield s)
proc scan(): int = read().parseInt
proc scanf(): float = read().parseFloat
proc toInt(c:char): int =
    return int(c) - int('0')



proc solve()=
  var
    q = scan() 
    abc = newseqwith(q,(scan(),scan(),scan()))

  
  for (a,b,c) in abc:
    var
      a = a
      cnt = 0
      ans = int.high.div(4)
    if c==1:
      echo -1
    else:
      while a>0:
        if a.mod(c)==0:
          a = a.div(c)
          cnt+=1
        else:
          ans = min(ans,cnt+(a+c-2).div(c-1))
          a -= (a.mod(c))
          cnt+=1
      ans = min(ans,cnt)
      echo ans*b

  
solve()