N,M,P,Q = map(int,input().split())

ANS = []

for lp in range(Q):

    x,f = map(int,input().split())

    y = f * pow(x,P-2,P) % P

    if y == 0:
        ANS.append( (M-y) // P )
    else:
        ANS.append( (M-y) // P + 1 )

print (*ANS,sep="\n")