#include <iostream>
using namespace std;

int count(int A, int B, int C)
{
    int i = 0;
    int c = 0;
    while (c < C)
    {
        i++;
        c += A;
        if (i % 7 == 0)
        {
            c += B;
        }
    }
    return i;
}
int main()
{
    int A, B, C;
    cin >> A >> B >> C;
    cout << count(A, B, C) << endl;
    return 0;
}
