def main():
    A, B, C, D = map(int, input().split())
    yasai = 0
    niku = 0
    
    for _ in range(A):
        yasai += 1
        niku += C
        if yasai + niku <= D:
            continue
        elif B < niku:
            print(yasai - 1)
        else:
            print(yasai - 1)
            break

if __name__ == '__main__':
    main()