#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0; i<(int)(n); i++)
#define all(vec) vec.begin(), vec.end()

int main() {
    int a, b, c;
    scanf("%d %d %d", &a, &b, &c);
    int ans;
    ans = c/(7*a+b)*7; 
    if ((c%(7*a+b)+a-1)/a >= 7) ans += 7;
    else ans += (c%(7*a+b)+a-1)/a;
    printf("%d\n", ans);
}
