#include<iostream>
using namespace std;
int Q;
main()
{
	cin>>Q;
	for(;Q--;)
	{
		long A,B,C;cin>>A>>B>>C;
		if(C==1)
		{
			cout<<-1<<endl;
			continue;
		}
		long ans=0;
		while(A)
		{
			if(A%C!=0&&A<=2*C-2)
			{
				if(A<C)ans+=B;
				else ans+=2*B;
				A=0;
			}
			else
			{
				if(A%C)ans+=B;
				if(A>=C)ans+=B;
				A/=C;
			}
		}
		cout<<ans<<endl;
	}
}