#include <iostream>
using namespace std;
int main(){
    long long a,b,n,day=1,sum=0,i=0;
    cin >> a >> b >> n;
    while (sum<n){
        if (day<=5) sum+=a;
        if (day==6) sum+=b;
        if (day==7){
            sum+=b;
            day=1;
        }
        day++;
        i++;
    }
    cout << i;
    return 0;
}