program permutation;
var
m,p : array [1..1000] of word;
N,i,j : integer;
k : longint;
quit : boolean;
Begin
  readln(N);
  for i := 1 to N do
   read(p[i]);
  for i := 1 to n do
   m[i]:=p[i];
  k:=1;
  quit := false;
  while true do begin
   j:=0;
   repeat
    j:=j+1;
    quit := m[j]=j;
   until (quit=false) or ((i=n) and (m[i]=i));
   if quit then break;
   k:=k+1;
   for i := 1 to n do
    m[i] := p[m[i]];
  end;
  writeln(K);
end.