Валидатор не пускает

package com.javarush.task.task14.task1420; import java.util.*; import java.io.*; /* НОД */ public class Solution { public static void main(String[] args) throws Exception { BufferedReader reader = new BufferedReader(new InputStreamReader(System.in)); int a = Integer.parseInt(reader.readLine()); int a2 = Integer.parseInt(reader.readLine()); if (a <= 0 || a2 <= 0) throw new Exception(); ArrayList<Integer> list = new ArrayList<>(); for(int i=1;i<a;i++){ if(a%i==0){ list.add(i); } } int max1 = Collections.max(list); ArrayList<Integer> list2 = new ArrayList<>(); for(int i=1;i<a2;i++){ if(a2%i==0){ list2.add(i); } } int max2 = Collections.max(list2); if(max1==max2){ System.out.println(max1); } if(max1!=max2){ int dilnuk = 0; if(max1>max2){ dilnuk = max1; }else if (max2>max1){ dilnuk = max2; } while(true){ if(a%dilnuk==0 && a2%dilnuk==0){ System.out.println(dilnuk); break; } dilnuk = dilnuk -1; } } } }