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