#include <iostream>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <limits>


static const int MOD = 1000000007;
using ll = int64_t;
using u32 = uint32_t;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

int main() {
    int a, b, c, d;
    cin >> a >> b >> c >> d;
    int ans = 0;
    for (int i = 0; i <= a; ++i) {
        for (int j = 0; j <= b; ++j) {
            if(i+j > d) continue;
            if(i*c <= j) ans = max(ans, i);
        }
    }
    cout << ans << "\n";
    return 0;
}