SPIRAL Pascal

var a:array[0..1000005] of int64;
    n,i,kc:longint;
    s:int64;
begin
    assign(input,'spiral.inp');reset(input);
    assign(output,'spiral.out');rewrite(output);
    read(n);
    a[1]:=n;kc:=2*n-2;
    for i:=2 to n do
    begin
        a[i]:=a[i-1]+kc;
        kc:=kc-2;
    end;
    s:=0;
    for i:=1 to n do s:=s+a[i];
    write(s);
    end.