public static void main(String[] args){
        int[] start={1,3,0,5,8,5};
        int[] end={2,4,6,7,9,9};
        int[][] activities=new int[start.length][3];
        ArrayList<Integer> ans=new ArrayList<>();
        for(int i=0;i< start.length;i++){
            activities[i][0]=i;
            activities[i][1]=start[i];
            activities[i][2]=end[i];
        }

        Arrays.sort(activities, Comparator.comparingDouble(o->o[2]));
        int maxAct=1;
        int lastEnd=activities[0][2];
        ans.add(activities[0][0]);
        for(int i=1;i<end.length;i++){
            if(lastEnd<=activities[i][1]){
                maxAct++;
                lastEnd=activities[i][2];
                ans.add(activities[i][0]);
            }
        }
        System.out.println(maxAct);
        System.out.println(ans);
    }