a,b,c,d=list(map(int,input().split()))
counter,hara=0,0
def f():
    if hara+c+1>d:
        return False
    if a==0:
        return False
    if b<c:
        return False
    return True
while f()==True:
    counter+=1
    hara+=c+1
    a-=1
    b-=c
print(counter)