Go: package main

import (
	"fmt"
	"strings"
	"bufio"
	"os"
	// "reflect"
	"strconv"
)

func oneLineInt(s string) []int {
	temp := strings.Split(s, " ")
	// fmt.Println(len(temp))
	ints := []int{}
	for _, elem := range(temp) {
		int_elem, _ := strconv.Atoi(elem)
		ints = append(ints, int_elem)
	}
	return ints
}

func coinCount(ints []int) int {
	cons := ints[0]
	bonus := ints[1]
	target := ints[2]
	count := 0
	day := 0
	var dc int
	for day_count, _ := range(make([]int, target)) {
		day++
		if day % 7 == 0 {
			count += bonus
		}
		count += cons
		if count >= target {
			dc = day_count + 1
			break
		}
	}
	return dc
}

func main() {
	scanner := bufio.NewScanner(os.Stdin)
	var txt string
	if scanner.Scan() {
		txt = scanner.Text()
	}
	ints := oneLineInt(txt)
	// fmt.Println(ints[1])
	// fmt.Println(reflect.TypeOf(ints[0]))
	result := coinCount(ints)
	fmt.Println(result)
}

C++: #include <cassert>
//PXjUXeZStdX
#include <cctype>
#include <cerrno>
#include <cfloat>
#include <ciso646>
#include <climits>
#include <clocale>
#include <cmath>
#include <csetjmp>
#include <csignal>
#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <ccomplex>
#include <cfenv>
#include <cinttypes>
#include <cstdbool>
#include <cstdint>
#include <ctgmath>
#include <cwchar>
#include <cwctype>

// C++
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <array>
#include <atomic>
#include <chrono>
#include <condition_variable>
#include <forward_list>
#include <future>
#include <initializer_list>
#include <mutex>
#include <random>
#include <ratio>
#include <regex>
#include <scoped_allocator>
#include <system_error>
#include <thread>
#include <tuple>
#include <typeindex>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
//#include <boost/foreach.hpp>
//#include <boost/range/algorithm.hpp>
//#include <boost/multiprecision/cpp_int.hpp>
#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define ll long long
#define Sort(v) sort(all(v))
//#define INF 1e9
#define LINF (1LL<<40)
#define END return 0
#define pb push_back
#define se second
#define fi first
#define pb push_back
#define all(v) (v).begin() , (v).end()
#define MP make_pair
#define int long long
#define umap unordered_map 
#define re0 return 0
using namespace std;
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};
// int dx[]={0,1,0,-1};
// int dy[]={1,0,-1,0};
typedef pair<int,int> P;

const long long MOD=1000000007LL;
bool isupper(char c){if('A'<=c&&c<='Z')return 1;return 0;}
bool islower(char c){if('a'<=c&&c<='z')return 1;return 0;}
bool iskaibun(string s){for(int i=0;i<s.size()/2;i++)if(s[i]!=s[s.size()-i-1])return 0;return 1;}
bool isnumber(char c){return ('0'<=c&&c<='9');}
bool isalpha(char c){return (isupper(c)||islower(c));}

template<typename T> 
void print(vector<T> v){
    for(int i=0;i<v.size();i++){
        if(i)cout<<" ";
        cout<<v[i];
    }
    cout<<endl;
}
int INF=1e18;

template<typename T>
void printendl(vector<T> v){
    for(auto date:v)cout<<date<<endl;
}

template<typename T>
void printvv(vector<vector<T>> v){
    for(int i=0;i<v.size();i++){
        for(int j=0;j<v[i].size();j++){
            if(j)cout<<" ";
            cout<<v[i][j];
        }
        cout<<endl;
    }
}

int ans=0;
int gcd(int a,int b){
    ans++;
    if(a<b)swap(a,b);
    if(b==0)return a;
    else return gcd(b,a%b);
}

int powl(int n,int p){
    int ret=1;
    for(int i=0;i<p;i++)ret*=n;
    return ret;
}

struct Edge{
    int to,cost;
};

struct S{
    int ans,num;
};

/*
map<int,int> prime_factor(int a,int b){
    map<int,int> ret;
    int n=min(a,b);
    for(int i=2;i*i<=min(a,b);i++){
        while(a%i==0 && b%i==0){
            ret[i]++;
            a/=i;
            b/=i;
        }
    }
    if(a!=1)ret[a]=1;
    if(b!=1)ret[b]=1;
    return ret;
}*/

map<int,int> prime_factor(int n){
    map<int,int> ret;
    for(int i=2;i*i<=n;i++){
        while(n%i==0){
            ret[i]++;
            n/=i;
        }
    }
    if(n!=1)ret[n]=1;
    return ret;
}

vector<bool> eratos(int n){
    vector<bool> prime(n,true);
    prime[0]=false;
    prime[1]=false;
    for(int i=2;i<=n;i++){
        if(prime[i]){
            for(int j=i+i;j<=n;j+=i){
                prime[j]=false;
            }
        }
    }
    return prime;
}

signed main (){
    int a,b,c;
    cin>>a>>b>>c;
    int i=0;
    for(i=0;;i++){
        c-=a;
        if(i%7==6){
            c-=b;
        }
        if(c<=0)break;
    }
    cout<<i+1<<endl;
    
    

    
}

/*
1 3 9
*/

C++: // Last Change: 12/19/2019 18:34:55.
#include <algorithm>
#include <array>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;
using ll = long long;

int main() {
  ll A, B, C;
  cin >> A >> B >> C;

  ll table[7] = {0};
  for (int i = 0; i < 7; ++i) {
    table[i] = A;
  }
  table[6] += B;

  ll day, score;
  day = score = 0;
  while (score < C) {
    score += table[day % 7];
    ++day;
  }

  cout << day << endl;
}

C++: #include <iostream>
using namespace std;

int main()
{
    int a,b,c;
    cin >> a >> b >> c;
    int coin = 0;
    int day = 0;

    while(coin < c){
        day++;
        coin += a;
        if(day%7 == 0){
            coin += b;
        }
    } 
    cout << day << endl;
    return 0;
}

C++: #include <iostream>
using namespace std;

int main(void){
    int a, b, c;
    cin >> a >> b >> c;
    int score = 0;
    for(int day = 1; ; day++) {
        score += a;
        if(day % 7 == 0) {
            score += b;    
        }
        if (score >= c) {
            cout << (day) << endl;
            break;
        }
    }
}

C++: #include<iostream>
#include<cstdio>
using namespace std;

int main(){
    int coin_d, coin_b, norma,day;
    scanf("%d %d %d",&coin_d,&coin_b,&norma);
    day = (norma/(coin_d*7+coin_b))*7;
    if((norma%(coin_d*7+coin_b))/coin_d >= 7){
        day = day+7;
    }else if((norma%(coin_d*7+coin_b))%coin_d > 0){
        day = day + (norma%(coin_d*7+coin_b))/coin_d + 1;
    }else{
        day = day + (norma%(coin_d*7+coin_b))/coin_d;
    }
    cout << day << endl;
    return 0;
}

C++: #include <bits/stdc++.h>
#define REP(i, n) for (long long i = 0; i < (long long)n; i++)
#define _GLIBCXX_DEBUG
#define ll long long
using namespace std;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll A, B, C;
    cin >> A >> B >> C;
    ll W = (7 * A) + B;
    ll T = C % W;
    cout << ((C / W) * 7) + min(7, (int)((T + A - 1) / A)) << endl;
}

C++: #include<bits/stdc++.h>
typedef long long int ll;
typedef unsigned long long int ull;
#define BIG_NUM 2000000000
#define HUGE_NUM 99999999999999999
#define MOD 1000000007
#define EPS 0.000000001
using namespace std;
 
 
 
 
int main(){
 
    int A,B,C;
 
    scanf("%d %d %d",&A,&B,&C);
 
    int ans = C,left = 0,right= C,mid = (left+right)/2;
 
    while(left <= right){
 
        if(mid*A+mid/7*B >= C){
 
            ans = mid;
            right = mid-1;
 
        }else{
 
            left = mid+1;
        }
        mid = (left+right)/2;
    }
 
    printf("%d\n",ans);
 
    return 0;
}