#include<iostream>
using namespace std;
int main() {
long long a, b, n, cnt = 1;
cin >> a >> b >> n;
long long sev=5*a+2*b;
long long temp=0;
if(n>sev){
long long bc=n/sev;
n=n%sev;
temp=7*bc;
}
while (n > 0) {
if (cnt % 7 == 0 || cnt % 6 == 0) {
n = n - b;
}
else {
n = n - a;
}
cnt++;
}
cout << cnt + temp - 1;
return 0;
}