var p,m,s:int64;
begin
assign(input,'fact.in');reset(input);  
assign(output,'fact.out');rewrite(output);  
readln(p);  
m:=0; s:=0;  
 if p<0 then write(-1)  
        else if p=0 then write(1)  
                    else  
 begin 
   for i:=1 to (p div 2) do
     if i mod 4=1 then inc(m); end;
s:=s*p-m*5;
write(s);
close(input);close(output);
end.