Given a positive integer K. Find the number of ordered pairs of positive integers (a,b) where 1≤a<b<K such that a+b ≤ K.

Example 1:
Input:
K = 2
Output:
0
Explanation:
There are no solutions for K = 2.
Example 2:
Input:
K = 4
Output:
2
Explanation:
There are 2 solutions:- (1,2) and (1,3).

Your Task:
You don't need to read input or print anything. Your task is to complete the function numOfWays() which takes an Integer K as input and returns the number of solutions for a and b (1≤a<b<K) such that a+b ≤ K.

Expected Time Complexity: O(1)
Expected Auxiliary Space: O(1)

Constraints:
1 <= K <= 10^{5}

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