Good Sequences
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Gửi bài giải
Điểm:
5,00 (OI)
Giới hạn thời gian:
1.0s
Giới hạn bộ nhớ:
512M
Input:
stdin
Output:
stdout
Nguồn bài:
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Ngôn ngữ cho phép
C, C++, Java, Kotlin, Pascal, PyPy, Python, Scratch
Reference: Codeforces 264B — Good Sequences
You are given ~n~ distinct positive integers:
~a_1, a_2, \ldots, a_n~
in strictly increasing order.
A sequence ~x_1, x_2, \ldots, x_k~ is called good when all the following conditions hold:
- Every element of the sequence belongs to the given set of integers.
- The sequence is strictly increasing.
- Every two adjacent elements have a greatest common divisor greater than ~1~.
Formally:
~gcd(x_i, x_{i+1}) > 1~
for every ~1 \le i < k~.
Find the maximum possible length of a good sequence.
Input
- The first line contains one integer ~n~.
- The second line contains ~n~ integers in strictly increasing order: ~a_1, a_2, \ldots, a_n~.
Output
- Print one integer: the maximum length of a good sequence.
Constraints
- ~1 \le n \le 10^5~
- ~1 \le a_i \le 10^5~
- ~a_i < a_{i+1}~
Example 1
Input:
5
2 3 4 6 9
Output:
4
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