#include<stdio.h>
struct Rectangle
{
    float length;
    float width;
};
float calculateArea(struct Rectangle r)
{
    return r.length * r.width;
}
int main()
{
    struct Rectangle rect;
    scanf("%f",&rect.length);
    scanf("%f"&rect.width);
    if(rect.length<0||rect.witdh<0)
    {
        printf("Invalid input");
    }
    else
    {
        float area=calculateArea(rect);
        printf("%.2f"area);
    }
    return 0;
}