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

  cin >> A >> B >> C;
  int Day=0;

  while(C>0){
    Day+=1;
    if(Day%7==0){
      C=C-A;
      C=C-B;
    }
    else{
      C=C-A;
    }
  }

  cout << Day << "\n";
}
