a,b,c,d = map(int,input().split())
if c+1 > d:
    print(0)
    exit()
for i in range(a):
    if d >= c+1:
        d -= c+1
    else:
        print(i)
        exit()
    if b >= c:
        b -= c
    else:
        print(i)
        exit()
print(a)