Longest Periodic Proper Prefix

class Solution {
    int getLongestPrefix(String s) {
        int n = s.length();
        int i = 0;
        int j = n - 1;
        int pos = n - 1;
        int ans = 0;
        while (j < n && pos > 0) {
            if (s.charAt(i) == s.charAt(j)) {
                i++;
                j++;
                ans++;
            } else {
                i = 0;
                pos--;
                j = pos;
                ans = 0;
            }
        }
        
        if (pos == 0)
            return -1;

        return n - ans;
    }
}