#include <iostream>
using namespace std;
typedef long long ll;
ll a, b, n;
int i , day, week,ans = 0;
int main()
{
	cin >> a >> b >> n;
	int x = n % (a* 5 + b * 2);
	week = n / (a * 5 + b * 2);
	for (int i = 1; i <= 7; i++)
	{
		if (x == 0)
		{
			ans = week * 7;
			break;
		}
		if (i <= 5) 
		{
			if (i * a >= x) {
				day = i;
				ans = week * 7 + day;
				break;
			}
			else
				continue;
		}
		if(i >5)
		{
			if ((5 * a + (i - 5) * b) >= x)
			{
				day = i;
				ans = week * 7 + day;
				break;
			}
			else
				continue;
		}
	}
	cout << ans;
	return 0;
}