Q=int(input())
X=[0]*Q

for i in range(Q):
    A,B,C=map(int,input().split())

    if C==1:
        X[i]=-1
        continue

    Memo={0:0}
    def f(x):
        if x in Memo:
            return Memo[x]

        if x%C:
            T=(x//C)*C
            M=min(f(T)+1,(x+C-2)//(C-1))
        else:
            M=min(f(x//C)+1,(x+C-2)//(C-1))

        Memo[x]=M
        return M

    X[i]=f(A)*B

print(*X,sep="\n")