program znachy2;uses crt;var n,l:integer;k,y:real;beginy:=0;readln(l);for n:=1 to l dobegink:=1/sqr(n);y:=k+y;end;writeln(y)end.
program znachy2;
uses crt;
var n,l:integer;
k,y:real;
begin
y:=0;
readln(l);
for n:=1 to l do
begin
k:=1/sqr(n);
y:=k+y;
end;
writeln(y)
end.