#include<stdio.h>
long long q,n,w,a,b;
    int day = 1;
int main()
{
	long long q,n,w,a,b;
    int day = 1;

    scanf("%lld%lld%lld", &a,&b,&n);
    q = 5 * a + 2 * b;
    w = n / q;
    n %= q;
       for(int i = 1;n > 0;i++ ,day++)
       {
        if(day < 6)
        {
            n -= a;
        }
        else
        {
            n -= b;
        }
       
        day += 7*w;
       
       }
       printf("%d", day);
   }