#include<stdio.h>

int main()
{
	int vegetables, meat, proportion, all;
	scanf("%d %d %d %d",&vegetables,&meat,&proportion,&all);
	int ans;
	for (ans = 0; ans <= vegetables; ans++)
	{
		if (meat < ans * proportion){
			break;
		}
		if (ans * (proportion + 1) > all){
			break;
		}
	}
	ans--;
	printf("%d\n", ans);
}