program zzn;
type
        arr=array[1..100]of integer;
var
        ans,i,j,n:longint;
        a:array[false..true]of arr;
        b:array[1..10000]of integer;
        map:array[1..10000]of longint;
procedure init;
begin
        assign(input,'officer.in');
        reset(input);
        assign(output,'officer.out');
        rewrite(output);
        readln(n);
        for i:=1 to n do readln(b[i]);
        for i:=1 to n do a[not(odd(1)),i]:=i;
end;
procedure closef;
begin
        close(input);
        close(output);
end;
function  ok(c:arr):boolean;
var
        i:integer;
begin
        for i:=1 to n do if c[i]<>i then exit(false);
        exit(true);
end;
procedure main;
var
        f1,f2:boolean;
begin
        ans:=0;
        for i:=1 to n do a[not(odd(1)),i]:=i;
        while true do
        begin
            inc(ans);
            f1:=not(odd(ans));
            f2:=(odd(ans));
            for i:=1 to n do a[f2,b[i]]:=a[f1,i];
            if ok(a[f2]) then
             begin
                 writeln(ans);
                 exit;
             end;
        end;
end;
function gcd(a,b:longint):longint;
begin
        if a=0 then exit(b) else
        exit(gcd(b mod a,a));
end;
function lcm(x,y:longint):qword;

begin
        exit(x*y div (gcd(x,y)));
end;
procedure main2;
var
        move:longint;
        ans2:qword;
begin
        for i:=1 to n do
        begin
            move:=1;
            j:=b[i];
            while j<>i do
            begin
               j:=b[j];
               inc(move);
            end;
            map[i]:=move;
        end;
        ans2:=lcm(map[1],map[2]);
        for i:=3 to n do
        begin
            ans2:=lcm(ans2,map[i]);
        end;
        writeln(ans2);
end;
begin
        init;
        if n<=100 then main else
        main2;
end.