program test3;
var n: integer;
function fun (n:integer):integer;
begin
if n=1 then exit(1)
else if n=2 then exit(2)
else if n=3 then exit(3)
else exit(fun(n-3)*fun(n-1));
end;
begin
readln(n);
writeln(fun(n));
end.
输入：7
输出：54