#include <bits/stdc++.h>

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = std::int64_t;
using P = std::tuple<int,int>;

int A, B, C, D;

int main(){
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    std::cin >> A >> B >> C >> D;

    int mx = 0;

    for(int i=0;i<=std::min(A, D);++i){
        int j = std::min(D - i, B);

        if(j >= C * i){
            mx = std::max(mx, i);
        }
    }

    std::cout << mx << std::endl;
}