VK Cup 2015 - Finals, online mirror
F
Clique in the Divisibility Graph
Codeforces
1500
原题
← EG →
翻译中…

As you must know, the maximum clique problem in an arbitrary graph is $*NP*$-hard. Nevertheless, for some graphs of specific kinds it can be solved effectively.

翻译中…

Just in case, let us remind you that a clique in a non-directed graph is a subset of the vertices of a graph, such that any two vertices of this subset are connected by an edge. In particular, an empty set of vertexes and a set consisting of a single vertex, are cliques.

翻译中…

Let's define a divisibility graph for a set of positive integers $*A* = {*a*_{1}, *a*_{2}, ..., *a*_{*n*}}$ as follows. The vertices of the given graph are numbers from set $*A*$, and two numbers $*a*_{*i*}$ and $*a*_{*j*}$ ($*i* ≠ *j*$) are connected by an edge if and only if either $*a*_{*i*}$ is divisible by $*a*_{*j*}$, or $*a*_{*j*}$ is divisible by $*a*_{*i*}$.

翻译中…

You are given a set of non-negative integers $*A*$. Determine the size of a maximum clique in a divisibility graph for set $*A*$.

翻译中…

Input

翻译中…

The first line contains integer $*n*$ ($1 ≤ *n* ≤ 10^{6}$), that sets the size of set $*A*$.

翻译中…

The second line contains $*n*$ distinct positive integers $*a*_{1}, *a*_{2}, ..., *a*_{*n*}$ ($1 ≤ *a*_{*i*} ≤ 10^{6}$) — elements of subset $*A*$. The numbers in the line follow in the ascending order.

翻译中…

Output

翻译中…

Print a single number — the maximum size of a clique in a divisibility graph for set $*A*$.

翻译中…

Note

翻译中…

In the first sample test a clique of size 3 is, for example, a subset of vertexes ${3, 6, 18}$. A clique of a larger size doesn't exist in this graph.

翻译中…

样例

Input #1
8
3 4 6 8 10 18 21 24
Output #1
3
InputCopy OutputCopy
题目信息
题号
566F
时间限制
1 s
内存限制
256 MB
标签
动态规划
数学
数论

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。