#include <bits/stdc++.h> using namespace std; int main() {

int a;
cin >> a;
int n = 10;
int t = 0;
int m = 3;
while (1) {
	if ( m == 1 || m == 2) {
		n = n + 7;
	}
	n = n - 1;
	m += 1;
	m %= 7;
	t = t + 1;
	if (n == a) {
		cout << t;
		return 0;
	}
}

return 0;

}