import java.util.*;
import java.lang.*;
import java.io.*;
class Ideone
{
{
int a,n;
double s=0,q=1;
Scanner in
= new Scanner
(System.
in); n=in.nextInt();
for(int i=1;i<=n;i++){
q=q*2;
s+=(2*i-1)/q;
}
}
}
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