#include
using namespace std;
void main()
{
int n;
int sum=1;
cin>>n;
if(n%2 == 0)
for(int i=1;i<=n;i++)<br> if(i%2==0)
sum*=i;
if(i%2==1)
for(int i=1;i<=n;i++)<br> if(i%2==1)
sum*=i;
cout<<sum<<endl;<br> system("pause");
}
------------------------------------------------
var
sum,i,n:integer;
begin
sum:=1;
readln(n);
if n mod 2 = 0 then
for i:=1 to n do
if i mod 2 = 0 then
sum:=sum*i;
if n mod 2 = 1 then
for i:=1 to n do
if i mod 2 = 1 then
sum:=sum*i;
writeln(sum);
end.