Consider an input file A1.txt. Each line of A1.txt consists of two numbers separated by space. Write a C++ program that reads the two numbers from each line and adds all the integers between those two numbers (starting from the first number and ending at the second. Show your output in B1.txt. Sample Input: 16 18 74 29 38 Sample Output: 21 2622 335 (For further clarification, the first line of the sample output was done by 1 + 2 + 3 + 4 + 5 + 6 = 21)