#include <stdio.h>
int main()
{
    int weight,speed;
    float balance,tilt;
    scanf("%d", &weight);
    scanf("%d", &speed);
    scanf("%d", &balance);
    scanf("%d", &tilt);
    if (weight<=0 || speed<=0|| balanced<=||tilt<=0)
    {
        printf("invalid input");
}else{
    float stability= (weight * speed)/(balanced*tilt);
    printf("%.2f",stability);
}
return 0;
}