#include <stdio.h>

int main(){
	// 野菜の数・肉の数・比率・許容量
	int vegetables, meat, proportion, all;
	scanf("%d%d%d%d",&vegetables,&meat,&proportion,&all);
	if(meat == all){
		printf("0");
	}else if(vegetables + meat < all){
		printf("%d",meat / proportion);
	}else{
		int tmp = all / (proportion + 1);
		if(tmp < vegetables){
			printf("%d",tmp);	
		}else{
			printf("%d",vegetables);
		}
		
	}
	
}