char = input().split(" ")
a = int(char[0])
b = int(char[1])
c = int(char[2])
d = int(char[3])

vegi_list = [0]
for vegi in range(a + 1):
    for meat in range(b + 1):
        if meat >= vegi * c and vegi + meat <= d:
            # print(vegi, meat)
            vegi_list.append(vegi)

print(max(vegi_list))