Count Next Element

Given a list of integers nums, return the number of elements x there are such that x + 1 exists as well.

Constraints

• n ≤ 100,000 where n is the length of nums

https://binarysearch.com/problems/Count-Next-Element

Examples

Example 1

Input

• nums = [3, 1, 2, 2, 7]

Output

• answer = 3

Explanation

We can take

• 1 since 1 + 1 exists in the list.
• 2 since 2 + 1 exists in the list.
• Another 2.

Solution