A13301. Ehab's REAL Number Theory Problem
编程题
普及/提高-
知识点
题目描述
You are given an array $a$ of length $n$ that has a special condition: every element in this array has at most 7 divisors. Find the length of the shortest non-empty subsequence of this array product of whose elements is a perfect square.
A sequence $a$ is a subsequence of an array $b$ if $a$ can be obtained from $b$ by deletion of several (possibly, zero or all) elements.
A sequence $a$ is a subsequence of an array $b$ if $a$ can be obtained from $b$ by deletion of several (possibly, zero or all) elements.
输入格式
The first line contains an integer $n$ ( $1 \le n \le 10^5$ ) — the length of $a$ .
The second line contains $n$ integers $a_1$ , $a_2$ , $\ldots$ , $a_{n}$ ( $1 \le a_i \le 10^6$ ) — the elements of the array $a$ .
The second line contains $n$ integers $a_1$ , $a_2$ , $\ldots$ , $a_{n}$ ( $1 \le a_i \le 10^6$ ) — the elements of the array $a$ .
输出格式
Output the length of the shortest non-empty subsequence of $a$ product of whose elements is a perfect square. If there are several shortest subsequences, you can find any of them. If there's no such subsequence, print "-1".
输入输出样例
输入 #1
3 1 4 6
输出 #1
1
输入 #2
4 2 3 6 6
输出 #2
2
输入 #3
3 6 15 10
输出 #3
3
输入 #4
4 2 3 5 7
输出 #4
-1
说明/提示
In the first sample, you can choose a subsequence $[1]$ .
In the second sample, you can choose a subsequence $[6, 6]$ .
In the third sample, you can choose a subsequence $[6, 15, 10]$ .
In the fourth sample, there is no such subsequence.
In the second sample, you can choose a subsequence $[6, 6]$ .
In the third sample, you can choose a subsequence $[6, 15, 10]$ .
In the fourth sample, there is no such subsequence.