Description: 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. Input Format: 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. Output Format: Print a single number — the maximum possible number of ribbon pieces. It is guaranteed that at least one correct ribbon cutting exists. Note: 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.