#include<stdio.h>
struct Rectangle {
    float length;
    float width;
};
float calculation(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.width<0){
          printf("Invalid input");
          return 0;
      }
      float area = calculateArea(rect);
      printf("%.2f",area);return 0;
}