import java.io.*;
public class a
{
  public static void main (String args[])
  {
    int a = 0;
    boolean caught = false;
    BufferedReader in = new BufferedReader (new InputStreamReader (System.in));
    do
      {
        try
        {
          caught = false;
          a = Integer.parseInt (in.readLine ());
        }
        catch (Exception d)
        {
          caught = true;
          System.err.println ("Enter a number.. '" + d.getLocalizedMessage () + "' isn't.");
        }
      }while(caught);
    System.out.println (a);
  }
}