sum(x^(2i)/i,i=1..n) -- pascal

var
  x,t,s : Real;
  i,n : Integer;
begin
  writeln('n= ');readln(n);
  writeln('x= ');readln(x);
  s:= 0; t:= 1; i:= 1;
  while i<=n do
  begin
    t:= t*x*x;
    s:= s+t/i;
    i:= i+1;
  end;
  writeln(s);
end.