#include<stdio.h>
 
 struct Rectangle {
     float length;
     float width;
 };
 float calculateArea(struct Rectangle
 r){
     return r.length * r.width;
 }
 int main(){
     struct Rectangle rect;
     if(scanf("%f", &rect.length) !=1 || rect.length < -10 || rect.length>100){
         printf("Invalid input");
         return 0;
     }
     if(scanf(rect.length < 0 || rect.length < 0){
         printf("Invalid input");
         return 0;
     }
     
     float area=calculateArea(rect);
     printf("%.2f\n" area);
     return 0;
 }