C#Exams 3. Programmer DNA (on Java Code)

import java.util.Scanner;

public class _3_ProgrammerDNA {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner scan = new Scanner(System.in);
        int length = scan.nextInt();
        char startLetter = scan.next().charAt(0);

        int indexLetter = startLetter - 65;
        int countOfFull7Rows = length / 7;
        for (int i = 0; i < countOfFull7Rows; i++) {
            indexLetter = printSevenOrLessRowsOfDNASequence(7, indexLetter);
        }
        int lastRowsOfSequence = length % 7;
        if (lastRowsOfSequence > 0) {
            printSevenOrLessRowsOfDNASequence(lastRowsOfSequence, indexLetter);
        }
    }

    private static int printSevenOrLessRowsOfDNASequence(int countRows,
            int indexLetter) {
        // TODO Auto-generated method stub
        int countLetters = 1;
        int outerDots = 3;
        String outerDotSeq;
        StringBuilder letterSeq;
        for (int row = 0; row < countRows; row++) {
            outerDotSeq = newString('.', outerDots);
            letterSeq = new StringBuilder();
            for (int count = 0; count < countLetters; count++) {
                indexLetter %= 7;
                char nextLetter = (char) (indexLetter + 65);
                letterSeq.append(nextLetter);
                indexLetter++;
            }

            System.out.printf("%1$s%2$s%1$s\n", outerDotSeq, letterSeq);

            if (row < 3) {
                outerDots--;
                countLetters += 2;
            } else {
                outerDots++;
                countLetters -= 2;
            }
        }

        return indexLetter;
    }

    private static String newString(char ch, int size) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < size; i++) {
            sb.append(ch);
        }

        return sb.toString();
    }

}