use std::io::{self, Write};
use std::iter;

fn make_passwords<W: Write>(patterns: &[Vec<u8>], buffer: &mut Vec<u8>, i: usize, writer: &mut W) {
    if i == patterns.len() {
        writer.write(&buffer).unwrap();
    } else {
        for c in patterns[i].iter() {
            buffer[i] = *c;
            make_passwords(patterns, buffer, i + 1, writer);
        }
    }
}

fn main() {
    let range = |a, b| (a as u8..b as u8 + 1).collect::<Vec<_>>();

    let patterns: Vec<Vec<u8>> = vec![
        range('a', 'z').into_iter().chain(range('1', '9').into_iter()).collect(),
        vec!('a' as u8, 'c' as u8),
        range('a', 'z'),
        range('a', 'z'),
        range('a', 'z')
    ];

    let mut buffer: Vec<u8> = vec!(0; patterns.len() + 1);
    buffer[patterns.len()] = '\n' as u8;

    let mut writer = io::BufWriter::new(io::stdout());
    make_passwords(&patterns, &mut buffer, 0, &mut writer);
}