CF189A.Cut Ribbon

Polycarpus has a ribbon, its length is n. He wants to cut the ribbon in a way that fulfils the following two conditions:

• After the cutting each ribbon piece should have length a, b or c.
• After the cutting the number of ribbon pieces should be maximum.

Help Polycarpus and find the number of ribbon pieces after the required cutting.

波利卡普斯有一条长度为 $n$ 的丝带。他希望将这条丝带剪成若干段，使得满足以下两个条件：

• 剪完后，每一段丝带的长度必须为 $a$、$b$ 或 $c$；
• 剪完后，丝带段数应尽可能多。

请帮助波利卡普斯，求出满足上述要求时丝带的最多段数。

The first line contains four space-separated integers n, a, b and c (1 ≤ n, a, b, c ≤ 4000) — the length of the original ribbon and the acceptable lengths of the ribbon pieces after the cutting, correspondingly. The numbers a, b and c can coincide.

第一行包含四个以空格分隔的整数 $n$、$a$、$b$ 和 $c$（$1 ≤ n, a, b, c ≤ 4000$），分别表示原始彩带的长度以及裁剪后彩带段的可接受长度。数字 $a$、$b$ 和 $c$ 可以相同。

Print a single number — the maximum possible number of ribbon pieces. It is guaranteed that at least one correct ribbon cutting exists.

输出一个整数——即彩带最多可被切成的段数。保证至少存在一种正确的彩带切割方案。

In the first example Polycarpus can cut the ribbon in such way: the first piece has length 2, the second piece has length 3.

In the second example Polycarpus can cut the ribbon in such way: the first piece has length 5, the second piece has length 2.

在第一个例子中，Polycarpus 可以这样剪裁彩带：第一段长度为 2，第二段长度为 3。

在第二个例子中，Polycarpus 可以这样剪裁彩带：第一段长度为 5，第二段长度为 2。