#python -m pdb a.py

J=lambda:map(int,input().split())
Z=-1<<128
def g(l,r,m,a,b,c,d):
	if l>r:return Z
	def f(x):return a*x+b*((c*x+d)//m)
	if c==0:return f(l if a<0 else r)
	L,R=(c*l+d)//m,(c*r+d)//m
	def h(x,y):x,y=max(x,L),min(y,R);return Z if x>y else b*(x if b<0 else y)
	if a<0:M=(c*l+d-c)//m;return max(h(L,min(R,M))+l*a,g(max(L,M+1),R,c,b+m//c*a,a,m%c,(-d+c-1)%c)+(-d+c-1)//c*a)
	return max(g(L,R-1,c,b+a*(m//c),a,m%c,(m-d-1)%c)+(m-d-1)//c*a,h(R,R)+r*a)
# [x/D] - [[x/A] * [AB/D] / B] <- x = Dy
# y - [[Dy/A] * [AB/D] / B]
# K < y - [[Dy/A] * [AB/D] / B]
# <=> [[Dy/A] * [AB/D] / B] < y - K
# <=> [Dy/A] * [AB/D] / B < y - K
# <=> [Dy/A] < B(y - K)/[AB/D]
# <=> BK < By - [AB/D][Dy/A]
for t in range(sum(J())):
	d,a,b,k=J();c,k,l,r=-(a*b//d),b*k,0,1<<128
	while l+1<r:
		m=(l+r)>>1
		if k<g(0,m,a,b,c,d,0):r=m
		else:l=m
	print(-1 if r>>128 else r*d)