#include <bits/stdc++.h>
using namespace std;

int main() {
  int A, B, C, P, N, Ans;
  cin >> A >> B >> C;
  P = 0;
  Ans = 0;
  N = 1000000;
  
  for (int i = 0; i < N; i++) {
    Ans++;
    P += A;
    if (Ans % 7 == 0) {
      P += B;
    }
    if (P >= C) {
      break;
    }
  }
  
  cout << Ans << endl;
  
  return 0;
}
