#include<iostream>
using namespace std;
int T;
main()
{
	cin>>T;
	for(;T--;)
	{
		int N,A,W,K;
		cin>>N>>A>>W>>K;
		if(N>K)
		{
			if(K-1<=A)
			{
				cout<<(A-(K-1))/K<<endl;
			}
			else if(N-K+1<=W)
			{
				cout<<-1<<endl;
			}
			else
			{
				cout<<":("<<endl;
			}
		}
		else
		{
			long S=A;
			long T=W/N;
			S-=T*(T+1)/2*N;
			S-=(T+1)*(W%N);
			S-=N-1;
			long s=S/N;
			while(s*N>S)s--;
			cout<<s<<endl;
		}
	}
}