#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int main() {
	ll a,b,c;
	ll day = 1,coin=0;
	cin >> a >> b >> c;

	while (true) {
	
		if (day % 7 == 0)
			coin += a + b;
		else
			coin += a;

		if (c <= coin)
			break;

		day++;
	}

	cout << day << endl;
		
}

