#include <bits/stdc++.h>
using namespace std;
int main() {
 int A,B,C ;
 int login=0;
 int coin=0;
 cin >> A >> B >> C;
 while(coin<C){
     coin = coin + A;
     login++;
     if(login%7==0){
         coin = coin + B;
     }
 }
 cout << login << endl;
}
