#include"bits/stdc++.h"
using namespace std;

int CEIL(int a, int b) {return (a - 1) / b + 1;}

int main(){

	int A, B, C;
	cin >> A >> B >> C;
	int weekly = 7 * A + B;
	int answer = 0;

	int week = C / weekly;
	answer = week * 7;
	C -= week * weekly;

	for(int day = 0; day < 7 && C > 0; day++){
		C -= A;
		answer++;
	}

	cout << answer << endl;

	return 0;
}
