The following function isTech( ) is a part of some class which is used to check if a given number…

The following function isTech( ) is a part of some class which is used to check if a given number is a Tech number or not. There are some places in the code marked by ?1? , ?2? , ?3? which may be replaced by a statement / expression so that the function works properly. A number is Tech number if the count of digits is even and the square of the sum of its two equal halves is equal to the number itself. Example: $2025 = 20 + 25 = (45)^2 = 2025$

boolean isTech(int n)
{
    String s = String.valueOf(n);
    int len = ?1?;
    if (len % 2 != 0)
        return ?2?;
    int first = Integer.parseInt(s.substring(0, len / 2));
    int second = Integer.parseInt(s.substring(len / 2));
    int sum = first + second;
    return ?3? == n;
}

What are the expressions or statements at ?1?, ?2? and ?3?