// Short way to check if prime fn is_prime(x: i64) -> bool { let last = (x as f64).sqrt() as i64 + 1; x > 1 && (2..last).all(|d| x % d != 0) }
// Short way to check if prime fn is_prime(x: i64) -> bool { let last = (x as f64).sqrt() as i64 + 1; x > 1 && (2..last).all(|d| x % d != 0) }