//2020国赛JAVA B 扩散
//多源BFS
//结果:20312088
import java.util.*;

public class Main {
    static class node{
        int x;
        int y;
        int time;
        node(int x,int y,int time){
            this.x=x;
            this.y=y;
            this.time=time;
        }
    }
    static int[] x= {-1,1,0,0};
    static int[] y= {0,0,-1,1};
    static boolean[][] vis=new boolean[10000][10000];
    //初始就有4个黑点
    static long ans=4;
    public static void bfs() {
        Queue<node> q=new LinkedList<node>();
        //将多个起点入队
        q.offer(new node(0+3000,0+3000,0));
        q.offer(new node(2020+3000,11+3000,0));
        q.offer(new node(11+3000,14+3000,0));
        q.offer(new node(2000+3000,2000+3000,0));
        //将初始起点标为走过
        vis[0+3000][0+3000]=true;
        vis[2020+3000][11+3000]=true;
        vis[11+3000][14+3000]=true;
        vis[2000+3000][2000+3000]=true;
        while(!q.isEmpty()) {
            node t=q.poll();
            if(t.time==2020) {
                return ;
            }
            for(int a=0;a<4;a++) {
                int newx=t.x+x[a];
                int newy=t.y+y[a];
                if(vis[newx][newy]==false) {
                    ans++;
                    vis[newx][newy]=true;
                    q.offer(new node(newx,newy,t.time+1));
                }
            }
        }
    }

    public static void main(String[] args) {
        bfs();
        System.out.println(ans);
    }
}