You are given an array of integers, nums, and you need to calculate the total concatenation value. To calculate this, you repeatedly perform the following operations until the array is empty:

1. If the array has more than one element, take the first and last elements, concatenate them, and add the result to the total concatenation value. Then remove the first and last elements from the array.
2. If the array has only one element, add it to the total concatenation value and remove the element.

The goal is to return the total concatenation value after performing all the operations.

Given an integer array nums of size n and two integers lower and upper, find the number of fair pairs. A pair (i, j) is considered fair if it satisfies the following conditions:

• 0 <= i < j < n
• lower <= nums[i] + nums[j] <= upper

Return the number of such pairs.

You are given a binary string s and a 2D array of queries. Each query is represented as [firsti, secondi], where firsti and secondi are integers. For each query, you need to find the shortest substring of s whose decimal value XORed with firsti equals secondi.

In other words, find a substring whose decimal value, when XORed with firsti, results in secondi. If such a substring exists, return its starting and ending indices (0-indexed). If no such substring exists, return [-1, -1].

If there are multiple valid substrings, return the one with the smallest starting index.