/* package codechef; // don’t place package name! */
import java.util.;
import java.lang.;
import java.io.*;
/* Name of the class has to be “Main” only if the class is public. */
class Codechef
{
public static void main (String[] args) throws java.lang.Exception
{
// your code goes here
Scanner sc = new Scanner(System.in);
double x= sc.nextDouble();
double y= sc.nextDouble();
sc.close();
if(x>y){
System.out.print(y);
}else if(x%5!=0){
System.out.print(y);
}else{
y=y-(0.50+x);
System.out.print(y);
}
}
}