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

    let mut result = 0usize;
    for i in 0.. {
        if i % 7 == 6 {
            n += 6;
        }
        n -= 1;
        result += 1;
        if n == 0 {
            break;
        }
    }
    println!("{}", result);
}