
#include <iostream>
#include <list>

int main()
{
	int A, B, C;
	std::cin >> A >> B >> C;

	int weekCoin = 7 * A + B;

	int weekNum = C / weekCoin;

	C -= weekNum * weekCoin;

	int dayNum =0;
	if (C / A >= 7) dayNum = 7;
	else dayNum = C / A + ((C%A) ? 1 : 0);
	
	
	std::cout << weekNum * 7 + dayNum << std::endl;

    return 0;
}

