For this Question: Given an integer N, find all possible pairs of A, and B such that A + B = N and A and B both are natural numbers.<b>User Task:</b>
Since this will be a functional problem, you don't have to take input. You just have to complete the function <b>Allpair()</b> that takes integer N as a parameter.

Constraints:-
1 &le; N &le; 10<sup>8</sup>Return the number of possible pairs of A and B.Sample Input:-
5

Sample Output:-
4

Explanation:-
(1, 4), (2, 3), (3, 2), (4, 1) are the only possible pairs.

Sample Input:-
2

Sample Output:-
1, I have written this Solution Code: int AllPair(int N){
return N-1;
}, In this Programming Language: C++, Now tell me if this Code is compilable or not?