import java.util.Random;
public class contains {
    public static void main(String [] args) {
        Random r=new Random(111111111111L);
        int n=Integer.parseInt(args[0]);
        int outer=8388608/n;
        int count=0;
        SList t=new SList();
        //Tree t=new Tree();
        for (int i=0; i<n; i++) {
            t.insert(r.nextInt(2*n));
        }
        for (int j=0; j<outer; j++) {
            for (int i=0; i<n; i++) {
                if (t.contains(r.nextInt(2*n))) {
                    count++;
                }
            }
        }
        System.out.println(count);
    }
}