#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
using namespace std;
typedef long long ll;
int INF = (1LL << 30) - 1;
int MOD = 1e9+7;
main(){
    int A,B,C,D;
    cin >> A >> B >> C >> D;
    for(int i = A;i >= 0;i--){
        if(A * C <= B && A + A * C <= D){
            cout << i << endl;
            return 0;
        }
    }
}