var a,i,s,x,j:longint;
begin
read(a);
for i:=1 to a do
begin
x:=1;
for j:=1 to i do
x:=x*j;
if i mod 2=0 then s:=s-x
else s:=s+x;
end;
write(s);
end.
/**************************************************************
	Problem: 1518
	User: admin
	Language: Pascal
	Result: Wrong Answer
****************************************************************/