program mire;
var f,g:text;
     poza,t,b,tt:array[1..30000] of integer;
     n,c,i,j,x:integer;
procedure citire;
var i,x:integer;
begin
assign(f,'tabara1.in'); reset(f);
   readln(f,n);
   for i:=1 to n do
    begin
     read(f,x);
       poza[x]:=i;
   end;
     readln(f);
   for i:=1 to n do
     begin
       read(f,x);
       t[i]:=poza[x];
     end;
close(f);
end;
function max(a,b:longint):longint;
        begin
                if a>b then
                        max:=a
                else
                max:=b;
end;
function cauta(xx,st,dr:longint):longint;
var m:longint;
begin
        while st<=dr do
        begin
                m:=(st+dr) div 2;
                if xx<=b[m] then dr:=m-1 else
                st:=m+1;
        end;
cauta:=st;
end;

begin
  citire;
  assign(g,'tabara1.out'); rewrite(g);
  b[1]:=t[1]; x:=1; tt[1]:=1;
  for i:=2 to n do
        begin
                j:=cauta(t[i],1,x);
                b[j]:=t[i];
                tt[i]:=j;
                x:=max(x,j);
        end;
    writeln(g,x);
  close(g);
end.