var
 a,b,ps1,ps2:array[0..5111]of longint;
 f:array[1..5111,1..5111]of longint;
 k,m,n,i,j:longint;

function max(const a,b:longint):longint;
begin
 if a>b then max:=a else max:=b;
end;

function find(x,y:longint):longint;
var
 j,res:longint;
begin
 res:=0;
 while x>0 do
 begin
  j:=y;
  while j>0 do
  begin
   res:=max(res,f[x,j]);
   j:=j and (j-1);
  end;
  x:=x and (x-1);
 end;
 find:=res;
end;

procedure modify(x,y,zn:longint);
var
 i,j:longint;
begin
 while x<=n do
 begin
  j:=y;
  while j<=m do
  begin
   f[x,j]:=max(f[x,j],zn);
   j:=(j or (j-1))+1;
  end;
  x:=(x or (x-1))+1;
 end;
end;

begin
 assign(input,'interview.in'); reset(input);
 assign(output,'interview.out'); rewrite(output);
 readln(n,m);
 for i:=1 to n do read(a[i]);
 for i:=1 to n do ps1[i]:=i;
 for i:=1 to m do read(b[i]);
 for i:=1 to m do ps2[i]:=i;

 for i:=1 to n do for j:=i+1 to n do if (a[j]<a[i])or(a[j]=a[i])and(ps1[i]<ps1[j]) then
 begin
  a[0]:=a[i];  a[i]:=a[j];  a[j]:=a[0];
  ps1[0]:=ps1[i]; ps1[i]:=ps1[j]; ps1[j]:=ps1[0];
 end;

 for i:=1 to m do for j:=i+1 to m do if (b[j]<b[i])or(b[j]=b[i])and(ps2[i]<ps2[j]) then
 begin
  b[0]:=b[i];  b[i]:=b[j];  b[j]:=b[0];
  ps2[0]:=ps2[i]; ps2[i]:=ps2[j]; ps2[j]:=ps2[0];
 end;

 for i:=1 to n do for j:=1 to m do if a[i]=b[j] then
 begin
  k:=find(ps1[i]-1,ps2[j]-1)+1;
  modify(ps1[i],ps2[j],k);
 end;
 writeln(find(n,m));
 close(output);
end.