#include<stdio.h>
struct Rectangle{
    double length;
    double width;
};
int main(){
    struct Rectangle rect;
    scanf("%f",&rect.length);
    scanf("%lf",&rect.width);
    if(rect.length<0||rect.width<0){
        printf("Invalid input\n");
    }
    else{
        printf("%.2lf\n",rect.length*rect.width);
    }
    return 0;
}