fn second_word(s: &String) -> &str {
    let bytes = s.as_bytes();
    let mut k = 0;
    let mut n =0;
    for (i, &item) in bytes.iter().enumerate() {
        if item == b' ' {
            k = k + 1;
            if k == 1 {
                n = i;
            }
            else if k == 2 {
                return &s[1+n..i];
            }

        }
    }

    &s[..]
}

fn add_unsafe(a: i32, b: i32) -> i32 {
  a + b
}

fn add_safer(a: i32, b: i32) -> std::io::Result<i32> {
  Ok(add_unsafe(a, b))
}

fn add_option(a: i32, b:i32) -> Option<std::io::Result<i32>> {
  Some(add_safer(a, b))
}

fn main() {
  println!("{:?}", add_option("4".parse::<i32>().unwrap(), "5".parse::<i32>().unwrap()).unwrap().unwrap());
}