type vector=array[1..20] of integer;

var  v:vector;
     n,p,h:integer;


{////////////////////////////}
{//////////validare//////////}
function valid(v:vector;k:integer):boolean;
var ok:boolean;
    i:integer;
begin
ok:=true;
for i:=1 to k-1 do
if v[k]=v[i] then
ok:=false;

valid:=ok;
end;
{/////////////////////////////}



procedure bk(var v:vector;n:integer);
var cont:boolean;
    k:integer;
begin
k:=1;
v[k]:=0;

while k>0 do
begin
cont:=false;
            while (v[k]<n) and (not cont) do
            begin
            v[k]:=v[k]+1;
            if valid(v,k) then
            cont:=true;
            end;
                if not cont then
                k:=k-1
                else
                if k=n then
                h:=h+1
                else
                begin
                k:=k+1;
                v[k]:=0;
                end;
end;
end;


begin




assign(input,'copii.in');
assign(output,'copii.out');

reset(input);
read(n);
close(input);

bk(v,n);

rewrite(output);
write(h div 2);
close(output);

end.