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

int main()
{
    int a,b,n;
    cin >> a >> b >> n;
    int day = 0;
    int moy = 0;
    while(moy < n)
    {
        for(int i = 1;i <= 5;i++)
        {
            moy += a;
            day++;
            if(moy >= n)
            {
                cout << day;
                return 0;
            }
        }
        for(int i = 1;i <= 2;i++)
        {
            moy += b;
            day++;
            if(moy >= n)
            {
                cout << day;
                return 0;
            }
        }
    }
    cout << day;
}