Given a natural number N, find the count of numbers from 1 to N that have an odd number of divisors.

Example 1:
Input:
N = 1
Output:
1
Explanation:
1 has only one
divisor {1}.

Example 2:
Input:
N = 4
Output:
2
Explanation:
4 has an odd number
of divisors {1, 2, 4}.

Your Task:
You don't need to read input or print anything. Your task is to complete the function oddNumberOfDivisor() which takes an integer N and returns the count of numbers from 1 to n that have an odd number of divisors.

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

Constraints:
1 <= N <= 10^{6}

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