def main():
    a, b, c, d = map(int, input().split(' '))

    vege = 0
    while (vege + 1) * (1 + c) <= d:
        if vege == a:
            print(vege)
            break
        if vege * c >= b:
            print(vege-1)
            break
        vege += 1
    else:
        print(vege)







if __name__ =='__main__':
    main()