import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

/**
 * <B>stdio</B> defines static methods for using typed input from the console window.
 * This class includes two methods for getting a line of input, two methods for
 * handling (i.e. parsing) typed-in numbers, and a simple rounding method so that
 * System.out.println won't print "0.33333333333333333" when you want to see "0.33".
 * <BR><BR>
 * <I>Known uses:</I> I have used this class successfully as a way to let my students
 * produce command-line applications that they can run in a MS-DOS command line window.
 * This lets them get started without first having to climb the learning curve for
 * Java GUI programming (AWT and Swing).
 * <BR><BR>
 * <I>Hints for use:</I> Put stdio.java and stdio.class into your project folder and
 * then use stdio in your project as you would use any other class.
 * <BR><BR>
 * @version 1.1 (added: end-of-stream situation in getLineTokens)
 * @author Unknown
 * @author Eugene Ageenko (v1.1 modifications)
 */
public class stdio {
    private static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    /**
     * Rounds a double to 2 or fewer digits to the right of the decimal point
     */
    public static double round2(double x) {
        return ((double) Math.round(x * 100)) / 100;
    }

    /**
     * Attempts to parse input string into an Integer.
     * @return null if it can't.
     */
    public static Integer parseInteger(String s) {
        try {
            return new Integer(s);
        } catch (NumberFormatException e) {
            return null;
        }
    }

    /**
     * Attempts to parse input string into a Double.
     * @return null if it can't.
     */
    public static Double parseDouble(String s) {
        int n;

        try {
            return new Double(s);
        } catch (NumberFormatException e) {
            return null;
        }
    }

    /**
     * Returns line of typed input as an array of Strings.
     * Each String in the array contains one word of the input.
     * Returns null.if the line is empty or end-of-stream occurs at the beginning,
     */
    public static String[] getLineTokens() {
        String line = getLine();
        StringTokenizer st;
        int nTokens;
        String[] tokens = null;

        if (line == null) return null; // end-of-stream
        if (line.length() > 0) {
            // we have a line
            st = new StringTokenizer(line);
            nTokens = st.countTokens();
            if (nTokens > 0) {
                // and that line has at least one word in it (e.g. not just spaces)
                tokens = new String[nTokens];
                for (int i = 0; i < nTokens; i++)
                    tokens[i] = st.nextToken();
            }
        }
        return tokens;
    }

    /**
     * Returns line of typed input as a String.
     * If the line is empty, returns a zero-length string "".
     * In case of end-of-stream and error, returns null.
     */
    public static String getLine() {
        try {
            return in.readLine();
        } catch (IOException e) {
            return null;
        }
    }
}