var n:longint;
    f1,f2:text;
begin
assign(f1,'fractii.in');reset(f1);
assign(f2,'fractii.out');rewrite(f2);
readln(f1,n);
if n=1 then write(f2,'1')
        else
                if (n>=2) and (n<=2) then write(f2,n*n-(n-1))
                        else
                                if (n>4) or (n=4) then write(f2,n*n-(n+1));
close(f1);
close(f2);
end.