In C++

Write a C++ program that prompts the user to input an integer (n) and outputs the sum of all integers i from 1 ton, but ifi = 2 is an integer) then i will have a negative sign For example, for n = 8 the sum is equal to - 1 - 2 + 3-4 +5 +6+7-8= 6, because 1, 2, 4 and 8 are 2, 21, 22 and 2 respectively while 3, 5, 6, and 7 are not equal to 2' for any integer). Note: Solve this question without defining any other function apart from the main function