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Formatted question description: https://leetcode.ca/all/2464.html

# 2464. Minimum Subarrays in a Valid Split

## Description

You are given an integer array nums.

Splitting of an integer array nums into subarrays is valid if:

• the greatest common divisor of the first and last elements of each subarray is greater than 1, and
• each element of nums belongs to exactly one subarray.

Return the minimum number of subarrays in a valid subarray splitting of nums. If a valid subarray splitting is not possible, return -1.

Note that:

• The greatest common divisor of two numbers is the largest positive integer that evenly divides both numbers.
• A subarray is a contiguous non-empty part of an array.

Example 1:

Input: nums = [2,6,3,4,3]
Output: 2
Explanation: We can create a valid split in the following way: [2,6] | [3,4,3].
- The starting element of the 1st subarray is 2 and the ending is 6. Their greatest common divisor is 2, which is greater than 1.
- The starting element of the 2nd subarray is 3 and the ending is 3. Their greatest common divisor is 3, which is greater than 1.
It can be proved that 2 is the minimum number of subarrays that we can obtain in a valid split.


Example 2:

Input: nums = [3,5]
Output: 2
Explanation: We can create a valid split in the following way: [3] | [5].
- The starting element of the 1st subarray is 3 and the ending is 3. Their greatest common divisor is 3, which is greater than 1.
- The starting element of the 2nd subarray is 5 and the ending is 5. Their greatest common divisor is 5, which is greater than 1.
It can be proved that 2 is the minimum number of subarrays that we can obtain in a valid split.


Example 3:

Input: nums = [1,2,1]
Output: -1
Explanation: It is impossible to create valid split.


Constraints:

• 1 <= nums.length <= 1000
• 1 <= nums[i] <= 105