program pi;

uses math;

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

begin
n := 0;
s := 0;
i := 1000000;

while n<=i do
        begin
        s := s+(power(-1,n)/(2*n+1));
        n := n+1;
        writeln('Pi: ',s*4);
        end
end.