Чудо техники

#pragma once
#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <iostream>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <vector>
#include <stdio.h>
#include <cmath>
#include <math.h>
#include <queue>
#include <stack>
#include <climits>
#include <deque>
#include <ctime>
#include <iomanip>
#include <bitset>
#include <unordered_map>
#include <unordered_set>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;

#define mh() make_heap()
#define poph() pop_heap()
#define pushh() push_heap()
#define sor(n) n.begin(), n.end()
#define rsor(n) n.rbegin(), n.rend()
#define mp make_pair
#define files freopen("input.txt", "rt", stdin); freopen("output.txt", "wt", stdout)
#define p(T) pair<T,T>
#define toch(x) cout.precision(x), cout.setf(ios::fixed)
#define znac(l) abs(l)/l
#define IOS ios::sync_with_stdio(false)
#define IOSB cin.tie(0), cout.tie(0);
const ll ok = ll(1e9 + 7);

int main()
{
    IOSB;
    IOS;
#ifdef TheCompiler
    files;
#endif
    ll m, k, d;
    cin >> k >> m >> d;
    ll answ = 0;
    ll frs = 0;
    ll pr = 1;
    for (int i = d; i <= 7; i++)
    {
        if (i != 7 && i != 6)
        {
            m += k;
        }
        if (m - pr < 0)
        {
            cout << i - d << endl;
            return 0;
        }
        m -= pr;
        pr++;
    }
    answ = 7 - d + 1;
    if (pr > k + m)
    {
        cout << answ << endl;
        return 0;
    }
    answ+=((k - pr) >= 0 ? (k - pr) : 0 * 6) / 7;
    pr += 7 * (((k - pr) >= 0 ? (k - pr) : 0 * 6) / 7);
    ll ost = ((k - pr)>=0? (k - pr):0 * 6) % 7;
    answ += ost;
    for (int i = ost; i <= 7; i++)
    {
        if (i != 7 && i != 6)
        {
            m += k;
        }
        if (m - pr < 0)
        {
            cout << answ+i-ost<< endl;
            return 0;
        }
        m -= pr;
        pr++;
    }
    answ += 7 - ost + 1;
    if ((2 * pr - 7) + 8 * m * 7 < 0)
    {
        for (int i = ost; i <= 7; i++)
        {
            if (i != 7 && i != 6)
            {
                m += k;
            }
            if (m - pr < 0)
            {
                cout << answ + i - ost << endl;
                return 0;
            }
            m -= pr;
            pr++;
        }
    }
    else
    {
        double dec = sqrt((2 * pr - 7) + 8 * m * 7);
        double x1 = ((-(2 * pr - 7)) + dec) / 14.0;
        double x2 = ((-(2 * pr + 7)) + dec) / 14.0;
        ll n;
        if (x1 < 0 || x2 < 0)
        {
            n = max(x1, x2);
        }
        else
        {
            n = min(x1, x2);
        }
        pr += 7 * (n - 1);
        m -= ((pr * 2 + 7 * (n - 1))*n) / 2;
        answ += n;
        for (int i = ost; i <= 7; i++)
        {
            if (i != 7 && i != 6)
            {
                m += k;
            }
            if (m - pr < 0)
            {
                cout << answ + i - ost << endl;
                return 0;
            }
            m -= pr;
            pr++;
        }
        answ += 7 - ost + 1;
    }
    cout << answ;
    return 0;
}