> var
>   a,b:array[1..1000] of integer;
>   n,k,i,j:longint;
> function over:boolean;
> var
>   i:integer;
> begin
>   over:=false;
>   for i:=1 to n do if b[i]<>i then exit;
>   over:=true;
> end;
> begin
>   readln(n);
>   fillchar(a,sizeof(A),0);
>   for i:=1 to n do read(a[i]);readln;
>   b:=a;
>   if over then writeln(0) else begin
>     j:=1;
>     while over=false do begin
>       inc(j);
>       for i:=1 to n do
>         b[i]:=a[b[i]];
>     end;
>     writeln(j);
>   end;
> end.
>