fn main() {
    let mut acc: u8 = 0;
    let mut s = *b"00: 0";

    for i in 5..30u8 {
        // Encode decimal number
        s[0] = 0;
        acc = i;
        loop {
            acc = acc.wrapping_sub(10);
            if acc & 0b1000_000 == 0 {
                s[0] += 1;
            } else {
                acc = acc.wrapping_add(10);
                break;
            }
        }
        s[1] = acc;

        s[0] += 0x30;
        s[1] += 0x30;


        s[4] = b'Y';
        'outer: for d in 2..=i / 2 {
            acc = i;
            loop {
                acc = acc.wrapping_sub(d);
                if acc == 0 {
                    // not prime!
                    s[4] = b'N';
                    break 'outer;
                }
                if acc & 0b1000_000 != 0 {
                    // not a divisor (subtraction overflowed)
                    break;
                }
            }
        }

        println!("{}", std::str::from_utf8(&s).unwrap());
    }
}