#include <iostream>
#include <cstring>
#include <algorithm>
using namespace std;
typedef long long LL;
LL a, b, n;
int main() {
cin >> a >> b >> n;
LL res = 0, cnt = 0;
res += 7 * ( n / (5 * a + 2 * b) );
n %= (5 * a + 2 * b);//剩余的天数
for (int i = 1; i <= 7; i ++)// 不超过7天
{
if (n <= 0) break; //终止条件写前面,因为剩余的天数可能为0
if (i <= 5) n -= a;
else n -= b;
res ++;
}
cout << res << endl;
return 0;
}