#include <iostream>
using namespace std;
typedef long long ll;
ll A,B,C,D;
int main(){
	cin >> A >> B >> C >> D;
	int l = 0,r = A+1;
	while(l+1<r){
		int m = (l+r)/2;
		if(m+m*C<=D && m*C<=B) l = m;
		else r = m;
	}
	cout << l << endl;
}