var
  n,m,i,j:longint;
  num:array[0..100000]of longint;
  f:array[0..1000,0..1000]of longint;

begin
  assign(input,'empire.in'); reset(input);
  assign(output,'empire.out'); rewrite(output);
  readln(n,m);
  for i:=1 to 2*n-1 do f[i,0]:=1;
  for i:=1 to 2*n-1 do num[i]:=2*((i+1) div 2)-1;
  f[1,1]:=1;
  for i:=2 to 2*n-1 do
   for j:=1 to i-1 do
    if i mod 2=1 then
    f[i,j]:=(f[i-1,j]+2*f[i-1,j-1] mod 504
    +(num[i]-2-(j-1))*f[i-1,j-1] mod 504) mod 504
    else f[i,j]:=(f[i-1,j]+(num[i]-(j-1))*f[i-1,j-1]) mod 504;
  if m<2*n-1 then writeln(f[2*n-1,m])
  else writeln(0);
  close(input);
  close(output);
end.