const DIVISOR: u64 = 10u64.pow(9) + 7;

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: u64 = n.trim().parse().unwrap();

    let mut c = (1, 0, 0);
    for _ in 0..n {
        c = ((c.1 + c.2) % DIVISOR, c.0, c.1);
    }

    println!("{}", (c.0 + c.1 + c.2) % DIVISOR);
}