Solution 1

import java.util.*;

 // Check Examples

 // Compiler version JDK 11.0.2

 class Dcoder
 {
    private static ArrayList<Integer> groups = new ArrayList<Integer>();

    public static void main(String args[])
    {
        Scanner input = new Scanner(System.in);
        int principal = input.nextInt();
        while(--principal > 0)
            addToGroup(shiftGroups(principal));

        if(groups.isEmpty()) groups.add(0);
        System.out.println(groups.size());
    }

    public static boolean shiftGroups(int amount) {
        if(groups.isEmpty()) return true;

        if(groups.size() == 100000-1) return false;
        if(groups.get(groups.size() - 1) < 3) return false;
        return true;
    }

    public static void addToGroup(boolean isShifting) {
        if(isShifting)
            groups.add(0);

        int index = groups.size() - 1;
        int newInt = groups.get(index) + 1;
        groups.set(index, groups.get(index) + 1);
    }
 }