BUYMILK HSGVinh Phuc L9 2015-2016

#define task "BUYMILK"

#include <iostream>
#include <cstdio>

using namespace std;

using ll = long long;
using ld = long double;

constexpr int N = 1e5 + 5;
ll A, B, C, D;

void Read()
{
    cin >> A >> B >> C >> D;
}

void Solve()
{
    if (B <= C - D) // Sữa hộp rẻ hơn sữa chai
        cout << A / B;
    else
    {
        ll l = 1, m, h = A / (C - D);

        while (l <= h)
        {
            m = (l + h) / 2;
            if (A >= (C - D) * m && A - (m - 1) * (C - D) >= C)
                l = m + 1;
            else
                h = m - 1;
        }

        ll ans = h; // Mua h chai sữa
        A -= h * (C - D);

        ans += A / B;

        cout << ans;
    }
}

int32_t main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }

    Read();
    Solve();
}