Codeforces Round 162 (Div. 1)
B
Good Sequences
Codeforces
1500
原题
← AC →
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Squirrel Liss is interested in sequences. She also has preferences of integers. She thinks $*n*$ integers $*a*_{1}, *a*_{2}, ..., *a*_{*n*}$ are good.

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Now she is interested in good sequences. A sequence $*x*_{1}, *x*_{2}, ..., *x*_{*k*}$ is called good if it satisfies the following three conditions:

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  • The sequence is strictly increasing, i.e. $*x*_{*i*} < *x*_{*i* + 1}$ for each $*i*$ $(1 ≤ *i* ≤ *k* - 1)$.
  • No two adjacent elements are coprime, i.e. $*gcd*(*x*_{*i*}, *x*_{*i* + 1}) > 1$ for each $*i*$ $(1 ≤ *i* ≤ *k* - 1)$ (where $*gcd*(*p*, *q*)$ denotes the greatest common divisor of the integers $*p*$ and $*q*$).
  • All elements of the sequence are good integers.
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Find the length of the longest good sequence.

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Input

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The input consists of two lines. The first line contains a single integer $*n*$ ($1 ≤ *n* ≤ 10^{5}$) — the number of good integers. The second line contains a single-space separated list of good integers $*a*_{1}, *a*_{2}, ..., *a*_{*n*}$ in strictly increasing order ($1 ≤ *a*_{*i*} ≤ 10^{5}; *a*_{*i*} < *a*_{*i* + 1}$).

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Output

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Print a single integer — the length of the longest good sequence.

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Note

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In the first example, the following sequences are examples of good sequences: [2; 4; 6; 9], [2; 4; 6], [3; 9], [6]. The length of the longest good sequence is 4.

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样例

Input #1
5
2 3 4 6 9
Output #1
4
InputCopy OutputCopy
Input #2
9
1 2 3 5 6 7 8 9 10
Output #2
4
InputCopy OutputCopy
题目信息
题号
264B
时间限制
2 s
内存限制
256 MB
标签
动态规划
数论

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