type
long=array[1..1000001] of integer;
var
ar,y,x:long;
a,c,d,j,nx,ny,k:longint;
Procedure Sum(var x,y:long; var nx,ny:longint);
var
p,q,nl,i:integer;
Begin
If nx>ny then nl:=nx
else nl:=ny;
p:=0;
For i:=1 to nl do
Begin
q:=x[i]+y[i]+p;
x[i]:=q mod 10;
p:=q div 10;
End;
If p=1 then
Begin
nx:=nl+1;
x[nx]:=1;
End
else
nx:=nl;
End;
Procedure DivLong(j:longint);
var
d:longint;
Begin
Fillchar(ar,sizeof(ar),0);
d:=200;
a:=10;
repeat
  dec(d);
if a>j then begin
 ar[d]:=a div j;
 a:=a mod j; end;
 a:=a*10;
until (a=0) or (d=0);{For k:=199 downto 190 do Write(ar[k]);WritelN;}
end;
begin
ny:=200;
readln(k);
For j:=1
 to k do
Begin
DivLong(j);
Sum(x,ar,nx,ny);
End;
Write(x[nx],'.');
For j:=nx-1 downto 1 do
Write(x[j]);
end.