uses crt;
var a:real;
    j:integer;
    z:char;
begin
repeat
     clrscr;
     writeln('Trtkal 2008 - http://fei.trtkal.net');
     writeln('-----------------------------------');
     a:=0;
     for j:=0 to 1000 do
         begin
              if j mod 2=0 then a:=a+(1/(2*j+1)) else a:=a-(1/(2*j+1));
         end;
     a:=a*4;
     writeln('Cislo PI mame priblizne: ',a);
writeln('----------');
write('Opakovat a/n: ');readln(z);
until (z='n');
end.