include

using namespace std;

int main() {

int n, m, k, c = 0;
cin >> n >> m >> k;
for (int i = n; i <= m; ++i) {
	if (k == 6 || k == 7) {
		++c;
	}
	k=++;
	if (k > 7)
		k = 1;
}
cout << c;
return 0;

}