import java.util.*;
class main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        if(!sc.hasNextInt()){
            System.out.print("Invalid input");
            return;
        }
        int a= sc.nextInt();
        float b= sc.nextDouble();
        if(a<=0 || b<=0){
            System.out.print("Invalid input");
            return;
        }
        System.out.printf("%.2f",a*b);
        
        
        
        
        
        
    }
}