fn dec2bin ( i: i32, f: bool ) {
    if f {
        print!("0b")
    }
    if i > 0 {
        dec2bin ( i/2, false );
        if i % 2 == 0 {
            print! ("0");
        } else {
            print! ("1");
        }
    }
}

fn main() {
    let input: i32 = 42;
    print!("{} in decimal: ", input);
    dec2bin ( input, true );
}