veg,meat,mul,limit = map(int,input().split())

vegs = []
for i in range(1,veg+1):
    for j in range(1,meat+1):
        if j == i*mul:
            if limit >= i+j:
                vegs.append(i)
            else:
                vegs.append(0)
        else:
            vegs.append(0)

print(max(vegs))