#include<stdio.h>

int main() {

	long long a, b, n;
	long long ret = 0;
	long long x = 0, y = 0;
	scanf_s("%llu %llu %llu", &a, &b, &n);
	while (ret < n) {
		int i = 0;
		int j = 0;
		while (i < 5) {
			ret = ret + a;
			i++;
			x++;
			if (ret >= n)
				break;
		}
		while (j < 2) {
			ret = ret + b;
			j++;
			y++;
			if (ret >= n)
				break;
		}

	}
	printf("%llu", x + y );
	return 0;
}