CF189A Cut Ribbon

给一长度为n的缎带，要求将其剪成若干长度为a,b,c的缎带，且缎带数量尽可能多。

输入仅一行，四个正整数n,a,b,c(n,a,b,c≤4000)。

输出仅一行，即缎带数量的最大值。

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.