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.

The first line contains four space-separated integers n, a, b and c (1 \le n,a,b,c \le 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.

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

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.