program xxxx;
var i,k,m,n,x,w:longint;
    a,mm:array[1..200000] of longint;
begin
  assign(input,'criminalc.in');
  reset(input);
  assign(output,'criminalc.out');
  rewrite(output);
  read(n,m,k);
  w:=0;
  for i:=1 to m do
    read(mm[i]);
  for i:=1 to n do
    begin
      read(a[i]);
      if (a[i]=k)or(a[i]=-k) then
        inc(w);
    end;
  for i:=1 to m do
    begin
      x:=mm[i];
      if (a[k]=x)or(a[k]=-x) then
        inc(w);
    end;
  write(w);
  close(input);
  close(output);
end.