program Kratne3;

{$APPTYPE CONSOLE}

var
i,s,n:integer;
begin
readln(n);
s:=0;
if n>10 then for i:=10 to n do if i mod 3=0 then s:=s+i;
if n<10 then for i:=n to 10 do if i mod 3=0 then s:=s+i;
writeln(s);
readln;
readln;
end.