#include <iostream>
using namespace std;
int a,b,n,day = 1,sum = 0,week = 1;
int main()
{
	cin >> a >> b >> n;
	while (sum < n)
	{
		if (week >= 1 && week <= 5) sum += a;
		else sum += b;
		week++;
		if (week == 8) week = 1;
		day++;
	}
	cout << day - 1 << endl;
	return 0;
}