fn repeated_string(s: &str, n: i64) -> i64 {
    let str_length = s.len();
    if str_length == 0 {
        return 0;
    }
    let a_count = s.bytes().filter(|&b| b == b'a').count();

    let modulo = n as usize % str_length;
    let remainder_count = s[..modulo].bytes().filter(|&b| b == b'a').count();

    let repeats = (n as usize) / str_length;
    (remainder_count + (a_count * repeats)) as i64
}