#include <bits/stdc++.h>
using namespace std;
long long a, b, c, x, k;
int main()
{
	cin >> a >> b >> c;
	x = c / (5 * a + 2 * b), c -= x * (5 * a + 2 * b);
	for (int i = 1;i <= 7;i++)
	{
		k++;
		if (i <= 5)
		{
			c -= a;
		}
		else
		{
			c -= b;
		}
		if (c <= 0)
		{
			break;
		}
	}
	cout << x * 7 + k;
	return 0;
}