program pi;

var
      n : real;
      s : real;
      i :  integer;

begin
   n := 0;
   s := 0;
   i := 1000000;
   while n<=i do
   begin
      s := s+(pow(-1,n)/(2*n+1));
      n := n+1;
      writeln("Pi: ",s*4);
   end
end