use std::io;

fn main() {
    print!("a = ");

    let mut a = String::new();
    io::stdin().read_line(&mut a).expect("Error");
    let a = convert_input(a);

    print!("b = ");
    let mut b = String::new();
    io::stdin().read_line(&mut b).expect("Error");
    let b = convert_input(b);

    let result = add(a, b);
    println!("{}", result);
}

fn convert_input(input: String) -> f32 {
    let output: f32 = match input.trim().parse() {
        Ok(num) => num,
        Err(msg) => {
            eprintln!("Error: {}", msg);
            std::process::exit(1);
        },
    };

    return output;
}

fn add(a: f32, b: f32) -> f32 {
    return a + b;
}