#include <iostream>
using namespace std;
int main() {
    int A, B, C;
    cin >> A >> B >> C;

    int goal = C;
    int d = 1;
    while (true) {
        goal -= A;
        if (goal <= 0) break;
        if (d % 7 == 0) goal -= B;
        if (goal <= 0) break;
        d++;
    }
    cout << d << endl;
    
    return 0;
}

