#include <bits/stdc++.h>
int main()
{
    int count1 = 0, count2 = 0, i = 0;
    long n, a, b, tmp;
    scanf("%ld %ld %ld", &a, &b, &n);
    tmp = n / (5 * a + 2 * b); // 周数
    while (count1 * a + count2 * b < n - tmp * (5 * a + 2 * b))
    {
        if (i < 5)
            count1++;
        else
            count2++;
        i = (i + 1) % 7;
    }
    printf("%ld", count1 + count2 + tmp * 7);
    return 0;
}