import sys
readline=sys.stdin.readline

T=int(readline())
for t in range(T):
    N,M,X,Y=map(int,readline().split())
    A=[(i*X+Y)%M for i in range(N)]
    B=[(i*X+Y)//M for i in range(N)]
    ans=sum(B[i]*(2*i-(N-1)) for i in range(N))
    for d in range(1,N):
        ans-=d*X//M*(N-d)
    print(ans)