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