#include <bits/stdc++.h>
using namespace std;
int main()
{
    long long a,b,n;
    cin>>a>>b>>n;
    int day = 0;
    int weekday = 0;
    long long sum = 0;
    while (true)
    {
        if (sum >= n)
        {
            break;
        }
        weekday += 1;
        day += 1;
        if (weekday == 8)
        {
            weekday = 1;
        }
        if (weekday <= 5 && weekday >= 1)
        {
            sum += a;
        }
        else
        {
            sum += b;
        }
    }
    cout<<day;
    return 0;
}