import java.awt.Point;
import java.util.HashSet;
import java.util.Random;

/**
 * 
 */

/**
 * random input generator for Collusion
 * 
 * Usage: java generator N 
 *   will generate a collection of N randomly selected points.
 *   Points will be normally clustered around (250, 250) and
 *   (750,750) with standard deviation 300.
 *    
 * @author zeil
 *
 */
public class generator {

    private int N;
    private Random rand;
    
    final static double stddev = 300.0;
    final static int mean1 = 250;
    final static int mean2 = 750;
    final int min = 0;
    final int max = 1000;
    
    /**
     * 
     */
    public generator(int n) {
        N = n;
        rand = new Random();
    }
    
    public void go() {
        HashSet<Point> points = new HashSet<Point>();
        System.out.println(N);
        for (int i = 0; i < N; ++i) {
            boolean done = false;
            while (!done) {
                int x = (int)(stddev * rand.nextGaussian());
                x += (i % 2 == 0) ? mean1 : mean2;
                x = Math.max(Math.min(x, max), min);
                int y = (int)(stddev * rand.nextGaussian());
                y += (i % 2 == 0) ? mean1 : mean2;
                y = Math.max(Math.min(y, max), min);
                Point p = new Point(x,y);
                if (!points.contains(p)) {
                    points.add(p);
                    System.out.println("" + x + " " + y);
                    done = true;
                }
            }
        }
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);
        if (n < 2 || n > 10000) n = 100;
        new generator(n).go();
    }

}