以下代码使用C++14（GCC9）并且用O2优化。样例全部AC，但是11号测试点TLE。

#include <iostream>
using namespace std;
int main(){
    long long a,b,n,c,count;
    int week = 1;
    cin >> a >> b >> n;
    c = 0;
    while (c < n){
        if (week >= 1 && week <= 5){
            c += a;
            week ++;
            count ++;
        }
        else if (week == 6){
            c += b;
            week ++;
            count ++;
        }
        else {
            c += b;
            count ++;
            week = 1;
        }
    }
    cout << count;
    return 0;
}