fn sum_str(a: &str, b: &str) -> i64 {
  let ra = a.to_string().parse::<i64>().unwrap();
  let rb = b.to_string().parse::<i64>().unwrap();

  ra + rb
}

fn main()
{
  let a = "a123";
  let b = "456";

  println!("{} + {} = {}", a, b, sum_str(a, b))
}