import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;

/** 
 * Read a line of input from System.in and convert the
 * entire line to a String or a number (int or a double).
 * 
 * Usage: 
 * Keyboard.readLine()   ==> next line of user input as a String 
 * Keyboard.readInt()    ==> next line of user input as an int
 * Keyboard.readDouble() ==> next line of user input as a double
 *
 * @author Suzanne Menzel
 */

public class Keyboard {  

  /** Reads and returns the next line of input as a String. */
  public static String readLine() {
    String line = "";

    try {
      line = reader.readLine();
    }
    catch (IOException e) {
      System.err.println("Error in Keyboard class:" + e);
      quit();
    }

    return line;
  }

  /** Reads and returns the next line of input as an int. */
  public static int readInt() {
    int n = 0;

    try {
      n = Integer.parseInt(readLine().trim());
    }
    catch (NumberFormatException e) { 
      System.err.println("Error in Keyboard.readInt()\n" + e);
      quit();
    }

    return n;
  }

  /** Reads and returns the next line of input as a double. */
  public static double readDouble() {
    double n = 0.0;

    try {
      n = Double.parseDouble(readLine().trim());
    }
    catch (NumberFormatException e) { 
      System.err.println("Error in Keyboard.readDouble()\n" + e);
      quit();
    }

    return n;
  }

  private static void quit() {
    throw new RuntimeException("read error");
  }

  private static BufferedReader reader = 
    new BufferedReader(new InputStreamReader(System.in)); 
}