import math
ABCD = input()
A = int(ABCD.split()[0])
B = int(ABCD.split()[1])
C = int(ABCD.split()[2])
D = int(ABCD.split()[3])
while D % (1+C) != 0:
    D -= 1
a_max = D / (C+1)
b_max = D * C / (C+1)
if a_max > A:
    a_max = A
    b_max = A*C
if b_max > B:
    while B % C != 0:
        B -=1
    b_max = B
    a_max = B/C
print(math.floor(a_max))