#include"stdio.h"
int main()
{
    int a,b,n,days;
    int t=1,T=0,w=1,i=1;
    scanf("%d %d %d",&a,&b,&n);
    for(i=1;a*t+b*T<n;i++,t++)
    {
        if(i==7*w)
        {
            t=t-3;
            T=T+2;
            w=w+1;
        }
    }
    days=t+T;
    printf("%d",days);
    return 0;
}