// editor1
#include<stdio.h>
typedef struct rectangle{
    float length;
    float breath;
}rectangle;

rectangle area(rectangle *r1){
    printf("%.2f",r1-length * r1.breath);
}

int main(){
    int len,wid;
    scanf("%d %d",&len,&wid);
    if(len<0 || wid<0){
        printf("Invalid input");
        return 0;
    }
    rectangle *r1 = {len,wid};
    area(r1);
    
    
}