#include<stdio.h>
struct Rectangle {
    float length;
    float width;
}];
float calculateArea(struct Rectangle r)
{
    return r . length * r.width;
}
int main() {
    struct Rectangle r;
    scanf("%f", &r . length);
     scanf("%f", &r . width);
     if (r.length < 0 || r . width < 0) {
         printf("Invalid input");
     } else {
         printf("%.2f", calculateArea(r));
     }
     return 0;
}