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

    let mut result = 0usize;
    for t in 0..=n/5 {
        for g in 0..=t {
            let val = t * 5 + g * 2;
            if val > n { break; }
            if (n - val) % 3 == 0 {
                result += 1;
            }
        }
    }
    println!("{}", result);
}