// Fill in your solution to encode, then compile and run the program.

import java.util.*;

public class Encode {
    public static String encode(String s, int n) {
        // fill in your solution here
        // you can also rename the parameters above
    }

    // this is the sample solution
    public static String encode2(String s, int n) {
        String result = "";
        for (int j = 0; j < n; j++) {
            for (int i = 0; i < s.length() - j; i += n) {
                result += s.charAt(i + j);
            }
        }
        return result;
    }

    private static int count, failCount;

    public static void main(String[] args) {
        String s = "";
        for (int i = 0; i < 10; i++) {
            s = s + i;
            for (int j = 2; j < s.length(); j++) {
                test(s, j);
            }
        }
        if (failCount == 0) {
            System.out.println("passed all tests");
        } else {
            System.out.println("failed " + failCount + " of " + count +
                               " tests");
        }
    }

    public static void test(String s, int n) {
        count++;
        System.out.println("testing encode(\"" + s + "\", " + n + ") ");
        String s1 = null;
        boolean fail = false;
        try {
            s1 = encode(s, n);
        } catch (RuntimeException e) {
            int line = e.getStackTrace()[1].getLineNumber();
            System.out.println("threw " + e + " at line #" + line);
            fail = true;
        }
        String s2 = encode2(s, n);
        System.out.println("correct = " + s2);
        if (!fail && !s1.equals(s2)) {
            System.out.println("theirs  = " + s1);
            fail = true;
        }
        if (fail) {
            System.out.println("failed");
            failCount++;
        } else {
            System.out.println("passed");
        }
        System.out.println();
    }
}