const ALPHABET_LENGTH = 26;
const UPPER_OFFSET = 'A' - ALPHABET_LENGTH;

const ALPHABET_LENGTH = 'z' - 'a' + 1;

        var seen = std.StaticBitSet(2 * 26).initEmpty();

        var seen = std.StaticBitSet(2 * ALPHABET_LENGTH).initEmpty();

                    seen.set(ch - UPPER_OFFSET);

                    seen.set(ch - 'A' + ALPHABET_LENGTH);

                    if (seen.isSet(ch - UPPER_OFFSET)) {

                    if (seen.isSet(ch - 'A' + ALPHABET_LENGTH)) {

                        prio += ch - UPPER_OFFSET + 1;

                        prio += ch - 'A' + ALPHABET_LENGTH + 1;

                    seen[counter % 3].set(ch - UPPER_OFFSET);

                    seen[counter % 3].set(ch - 'A' + ALPHABET_LENGTH);