var: sec,a,s,d,f,g: real;
begin
read(sec);
if (sec=<0) and (sec>=3927.273)
then
writeln('3927.273');
if (sec>3927.273) and (sec>=7854.546)
then
writeln('7854.546');
if (sec>7854.546) and (sec>=11781.819)
then
writeln('11781.819');
if (sec>11781.819) and (sec>=15709.092)
then
writeln('15709.092');
if (sec>15709.092) and (sec>=19636.365)
then
writeln('19636.365');
if (sec>19636.365) and (sec>=23563.638)
end.