The Happy Farm 5 creators decided to invent the mechanism of cow grazing. The cows in the game are very slow and they move very slowly, it can even be considered that they stand still. However, carnivores should always be chased off them. 

For that a young player Vasya decided to make the shepherd run round the cows along one and the same closed path. It is very important that the cows stayed strictly inside the area limited by the path, as otherwise some cows will sooner or later be eaten. To be absolutely sure in the cows' safety, Vasya wants the path completion time to be minimum.

The new game is launched for different devices, including mobile phones. That's why the developers decided to quit using the arithmetics with the floating decimal point and use only the arithmetics of integers. The cows and the shepherd in the game are represented as points on the plane with integer coordinates. The playing time is modeled by the turns. During every turn the shepherd can either stay where he stands or step in one of eight directions: horizontally, vertically, or diagonally. As the coordinates should always remain integer, then the length of a horizontal and vertical step is equal to 1, and the length of a diagonal step is equal to <image>. The cows do not move. You have to minimize the number of moves the shepherd needs to run round the whole herd.

Input

The first line contains an integer N which represents the number of cows in the herd (1 ≤ N ≤ 105). Each of the next N lines contains two integers Xi and Yi which represent the coordinates of one cow of (|Xi|, |Yi| ≤ 106). Several cows can stand on one point.

Output

Print the single number — the minimum number of moves in the sought path.

Examples

Input

4
1 1
5 1
5 3
1 3


Output

16

Note

Picture for the example test: The coordinate grid is painted grey, the coordinates axes are painted black, the cows are painted red and the sought route is painted green.

<image>
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {

	static InputStreamReader inp = new InputStreamReader(System.in);
	static BufferedReader in = new BufferedReader(inp);
	static boolean test = false;
	static PrintWriter writer = new PrintWriter(System.out);

	static String testDataFile = "testdata.txt";
	BufferedReader reader = null;

	public Main() throws Throwable {
		if (test) {
			reader = new BufferedReader(new FileReader(new File(testDataFile)));
		}
	}

	class Point implements Comparable<Point> {
		long x;
		long y;
		Point pv;

		public void setPivot(Point pivot) {
			this.pv = pivot;
		}

		public Point(int x, int y) {
			this.x = x;
			this.y = y;
		}

		public Point(int[] is) {
			x = is[0];
			y = is[1];
		}

		/**
		 * left-oriented first in the list
		 */
		public int compareTo(Point p) {
			long orientation = (p.x - pv.x)*(y - pv.y) - (x - pv.x)*(p.y - pv.y);
			if(orientation == 0){
				return Math.abs(x- pv.x) + Math.abs(y - pv.y)< Math.abs(p.x - pv.x) + Math.abs(p.y - pv.y)? -1 : 1;
			}
			return orientation > 0 ? 1 : -1;
		}

		@Override
		public String toString() {
			return "Point x=" + x + ", y=" + y + "]";
		}

		@Override
		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;
			Point other = (Point) obj;
			if (!getOuterType().equals(other.getOuterType()))
				return false;
			if (x != other.x)
				return false;
			if (y != other.y)
				return false;
			return true;
		}

		private Main getOuterType() {
			return Main.this;
		}

		
	}

	private void solve() throws Throwable {
		// Graham scan, first test
		int nodeCount = readInteger();
		
		if(nodeCount == 1){
			System.out.println("4");
			return;
		}
		
		List<Point> points = new ArrayList<Point>();
		
		long minY = Integer.MAX_VALUE;
		long minX = Integer.MAX_VALUE;
		int minId = 0;
		
		for (int i = 0; i < nodeCount; i++) {
			Point point = new Point(readIntegers());
			if(point.y < minY || (point.y == minY && point.x < minX)){
				minId = i;
				minY = point.y;
				minX = point.x;
			}
			points.add(point);
		}
		
		final Point startPoint = points.get(minId);
		points.remove(startPoint);
		for (Point point : points) {
			point.setPivot(startPoint);
		}
		
		Collections.sort(points);
		
		points.add(0, startPoint);
		
		
		Stack<Point> stack = new Stack<Point>();
		stack.push(points.get(0));
		stack.push(points.get(1));
		
		
		for (int i = 2; i < points.size(); i++) {
			Point p = points.get(i);
			Point p1 = stack.get(stack.size() -2);
			Point p2 = stack.get(stack.size() -1);
			long ccw = ccw(p1,p2,p);

			if(ccw == 0){
				stack.pop();
				stack.push(p);
			} else if (ccw > 0){
				stack.push(p);
			} else {
				while(ccw < 0 && stack.size() > 2){
					stack.pop();
					p1 = stack.get(stack.size()-2);
					p2 = stack.get(stack.size()-1);
					ccw =  ccw(p1,p2,p);
				}
				stack.push(points.get(i));
			}
			
		}
		
		stack.add(startPoint);
		
		int res = 0;
		
		for (int i = 0; i < stack.size() - 1 ; i++) {
			res += Math.max(Math.abs(stack.get(i).x - stack.get(i+1).x),Math.abs(stack.get(i).y - stack.get(i+1).y));
		}
		
		System.out.println(res+4);
	}
	
	
	long ccw(Point p1,Point p2,Point p3){
		return (p2.x - p1.x)*(p3.y - p1.y) - (p2.y - p1.y)*(p3.x - p1.x);
	}
	    

	/**
	 * The I/O method of reading
	 */
	int id = -1;

	public String readLine() throws IOException {
		id++;
		if (test)
			return reader.readLine();
		else
			return in.readLine();
	}

	/**
	 * read a single integer should be a full line
	 */
	private int readInteger() throws NumberFormatException, IOException {
		return Integer.valueOf(readLine());
	}

	/**
	 * Read one line and split contents to an int array
	 */
	private int[] readIntegers() throws Exception {
		String[] split = readLine().split(" ");
		int[] list = new int[split.length];
		for (int i = 0; i < list.length; i++) {
			list[i] = Integer.parseInt(split[i]);
		}
		return list;
	}

	/**
	 * Entry point
	 */
	public static void main(String[] args) throws Throwable {
		new Main().solve();
	}
}