C. Make a Square
brute force; implementation; math
You are given a positive integer \(n\), written without leading zeroes (for example, the number 04 is incorrect). In one operation you can delete any digit of the given integer so that the result remains a positive integer without leading zeros.Determine the minimum number of operations that you need to consistently apply to the given integer \(n\) to make from it the square of some positive integer or report that it is impossible.An integer \(x\) is the square of some positive integer if and only if \(x=y^2\) for some positive integer \(y\).
The first line contains a single integer \(n\) (\(1 \le n \le 2 \cdot 10^{9}\)). The number is given without leading zeroes.
If it is impossible to make the square of some positive integer from \(n\), print -1. In the other case, print the minimal number of operations required to do it.
In the first example we should delete from \(8314\) the digits \(3\) and \(4\). After that \(8314\) become equals to \(81\), which is the square of the integer \(9\).In the second example the given \(625\) is the square of the integer \(25\), so you should not delete anything. In the third example it is impossible to make the square from \(333\), so the answer is -1.