#include "bits/stdc++.h"
#define in std::cin
#define out std::cout
#define rep(i,N) for(LL i=0;i<N;++i)
typedef long long int LL;

int main()
{
	LL A, B, C, D;
	in >> A >> B >> C >> D;

	for (LL i = A; i >= 0; --i)
	{
		LL want = i * C;
		if (want + i > D) continue;
		if (want <= B)
		{
			out << i << std::endl;
			return 0;
		}
	}
}