use rand::Rng;
fn main() {
    let mut number: i128 = 0;
    loop {
        let rng: i128 = rand::thread_rng().gen_range(1..=1000000000000000000000000);
        println!("Do you want to add {} to the number", rng);
        println!("Your number is {}(y/n)", number);
        let mut input: String = String::new();
        std::io::stdin()
            .read_line(&mut input)
            .expect("Failed to read line");
        let input = input.trim(); // Parse is for numbers we use letters here. A &str is more usefull in this case as we dont want to mutate  it
        match input { // Match is a better way then chaining if/else expressions.
            "y" => number += rng, // let expression would have shadowed the original variable and would have droped to soon. Use add assign insted
            "n" => continue,
            _ => {
                println!("Option unknown")
            }
        }
    }
}