Q=int(input())
for q in range(Q):
    A,B,C=map(int,input().split())
    inf=1<<30
    def solve(A):
        retu=(A+C-2)//(C-1)*B
        if A:
            if A%C:
                retu=min(retu,solve(A-A%C)+B)
            else:
                retu=min(retu,solve(A//C)+B)
        return retu
    if C==1:
        ans=-1
    else:
        ans=solve(A)
    print(ans)