import java.util.stream.IntStream; public class IteratedDigitsSquaring { public static void main(String[] args) { long r = IntStream.range(1, 100_000_000) .parallel() .filter(n -> calc(n) == 89) .count(); System.out.println(r); } private static int calc(int n) { while (n != 89 && n != 1) { int total = 0; while (n > 0) { total += Math.pow(n % 10, 2); n /= 10; } n = total; } return n; } }