program fact;
var
 vector:array[0..12] of longint= (1, 6, 31, 156, 781, 3406, 17031, 85156, 425781, 2128906, 10644531, 53222656, 1000000001);
 p,zerouri:longint;
 marime,i:byte;
 fin,fout:text;
begin
 assign(fin,'fact.in');
 reset(fin);
 read(fin,p);
 close(fin);
 marime:=0;
 while p>vector[marime] do
  marime:=marime+1;
 zerouri:=p;
 for i:=marime downto 1 do
  zerouri:=zerouri-p div vector[i];
 assign(fout,'fact.out');
 rewrite(fout);
 write(fout,zerouri*5);
 close(fout);
end.