import java.util.*;
public class Main {
public static void main(String[] args) {
double x;
int a=-1;
double c;
double d=0;
Scanner in=new Scanner(System.in);
x=in.nextDouble();
for(int i=1;i<=10;i++) {
a=a+2;
c=Math.pow(-1, i+1);
long b=1;
for(int m=1;m<=a;m++) {
b=bm;
}
d=d+cMath.pow(x, a)/b;
}
System.out.println(String.format("%.3f",d));
}
}