import java.util.*;
class Main
{
{
Scanner scan
= new Scanner
(System.
in); int e=1;
double t, o=0;
int n = scan.nextInt();
double x = scan.nextDouble();
for (int j=1; j<(n+1); j++){
e*=2;
o+=t/e;
}
System.
out.
printf("%1$.6f", o
); }
}
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