#include<iostream>
using namespace std;
typedef long long ll;
int main(){
ll a,b,n;
ll day=0;
cin>>a>>b>>n;
ll one_week=5*a+2*b;
day+=7*(n/one_week);
ll res=n%one_week;
if(res<=a&&res){//余数小于一天的数量
day++;
}
else if(res>a&&res<=a*5){//余数在周一至周五数量内
day+=res/a;
if(res%a) day++;
}
else if(res>a*5){//余数达到了周末
day+=5;
res-=5*a;
if(res<b) day++;
else day+=2;
}
cout<<day;
return 0;
}