XUATHIEN PASCAL

const max = 10000000;
var a,b:array[1..max] of longint;
    m,n:longint;
procedure qs(l,h:longint);
var x,i,j,t:longint;
begin
    x:=b[(l+h) div 2];
    i:=l;j:=h;
    repeat
        while b[i] < x do inc(i);
        while b[j] > x do dec(j);
        if i<=j then
        begin
            t:=b[i];b[i]:=b[j];b[j]:=t;
            inc(i);dec(j);
        end;
    until i>j;
    if L<j then qs(L,j);
    if i<H then qs(i,H);
end;

function search(x:longint):byte;
var l,r,m:longint;
begin
    l:=1;r:=n;
    repeat
        m:=(l+r) div 2;
        if b[m]=x then exit(1)
        else
            if b[m]>x then r:=m-1
            else l:=m+1;
    until l>r;
    exit(0);
end;

procedure enter;
var i:longint;
begin
    readln(m, n);
    for i:=1 to m do readln(a[i]);
    for i:=1 to n do readln(b[i]);
end;

procedure solve;
var d,i:longint;
begin
    qs(1,n);
    d:=0;
    for i:=1 to m do
        inc(d,search(a[i]));
    writeln(d);
end;


BEGIN
    assign(input,'xuathien.inp');reset(input);
    assign(output,'xuathien.out');rewrite(output);
    enter;
    solve;
    close(input);close(output);
END.