package day02;

import java.util.Scanner;

public class Demo05 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextInt();
		long b = sc.nextInt();
		long n = sc.nextInt();
		long cnt = 0;
		int today = 0;
		while(n > 0) {
			if(today < 5) {
				n-=a;
			}else {
				n-=b;
			}
			today++;
			today%=7;
			cnt++;
		}
		System.out.println(cnt);
	}
}