#include<stdio.h>

int main(){
	// 入力された値
	double ratio1, overall1;
	scanf("%lf%lf",&ratio1,&overall1);
	printf("比率1：%f 全体1：%f\n",ratio1,overall1);
	
	double ratio2, overall2;
	scanf("%lf%lf",&ratio2,&overall2);
	printf("比率2：%f 全体2：%f\n",ratio2,overall2);
	
	// 1回に作る分量
	double quantity1 = overall1 / ratio1;
	double quantity2 = overall2 / ratio2;
	printf("分量1：%f 分量2：%f\n",quantity1,quantity2);
	
	// 全体製造量
	double ans = 0;
	while(0 <= overall1 && 0 <= overall2){
		overall1 -= quantity1;
		overall2 -= quantity2;
		printf("計算後\n全体1：%f 全体2：%f",overall1,overall2);
		ans += (quantity1 + quantity2);
		printf("製造量:%f\n",ans);
	}
	printf("%f",&ans);
}