import java.io.*;

class Keyboard {

// Author: M. Dennis Mickunas, June 9, 1997
// Primitive Keyboard input of integers, reals,
// strings, and characters.

static boolean iseof = false;
static char c;
static int i;
static double d;
static String s;
static BufferedReader input 
       = new BufferedReader (
              new InputStreamReader(System.in));

  public static int readInt () {
    if (iseof) return 0;
    System.out.flush();
    try { 
      s = input.readLine(); 
    }
    catch (IOException e) {
      System.exit(-1);
    }
    if (s.length()==0) {     // ctrl-C
      iseof=true; 
      return 0;
    }
    i = new Integer(s.trim()).intValue();
    return i;
  }

  public static char readChar () {
    if (iseof) return (char)0;
    System.out.flush();
    try { 
      i = input.read(); 
    }
    catch (IOException e) {
      System.exit(-1);
    }
    if (i == -1) {
      iseof=true; 
      return (char)0;
    }
    return (char)i;
  }

  public static double readDouble () {
    if (iseof) return 0.0;
    System.out.flush();
    try { 
      s = input.readLine();
    }
    catch (IOException e) {
      System.exit(-1);
    }
    if (s.length()==0) {
      iseof=true; 
      return 0.0;
    }
    d = new Double(s.trim()).doubleValue();
    return d;
  }

  public static String readString () {
    if (iseof) return null;
    System.out.flush();
    try { 
      s=input.readLine();
    }
    catch (IOException e) {
      System.exit(-1);
    }
    if (s==null) {
      iseof=true; 
      return null;
    }
    return s;
  }

  public static boolean eof () {
    return iseof;
  }

}