/KIVU - Khiêu vũ

              uses crt;
        var a,b:array[1..100000] of longint;
            n,m,i,d,j:longint;
        procedure sort(l,r:longint);
         var i,j,x,y:longint;
         begin
                i:=l;
                j:=r;
                x:=a[(l+r) div 2] ;
                repeat
                 while a[i]<x do inc(i);
                 while a[j]>x do dec(j);
                 if not (i>j) then
                  begin
                        y:=a[i];
                        a[i]:=a[j];
                        a[j]:=y;
                        inc(i);dec(j);
                  end;
                 until i>j;
                 if l<j then sort(l,j);
                 if i<r then sort(i,r);
         end;
        procedure sortb(l,r:longint);
         var i,j,x,y:longint;
         begin
                i:=l;
                j:=r;
                x:=b[(l+r) div 2] ;
                repeat
                 while b[i]<x do inc(i);
                 while b[j]>x do dec(j);
                 if not (i>j) then
                  begin
                        y:=b[i];
                        b[i]:=b[j];
                        b[j]:=y;
                        inc(i);dec(j);
                  end;
                 until i>j;
                 if l<j then sortb(l,j);
                 if i<r then sortb(i,r);
         end;
        begin
                readln(n,m);
                for i:=1 to n do read(a[i]);
                for j:=1 to m do read(b[j]);
                 sort(1,n);
                 sortb(1,m);
                i:=n;
                j:=m;
                d:=0;
                while (j>0) and (i>0) do
                 if a[i]>b[j] then
                   begin
                     d:=d+1;
                    dec(i);dec(j);
                   end
                 else  dec(j);
                write(d);
        end.