program hedianzhanwenti;
var
  f:array[1..50,0..5]of int64;
  i,j,k,n,m:longint;
  sum:int64;
begin
  assign (input,'nucle.in');
  reset (input);
  assign (output,'nucle.out');
  rewrite (output);
    readln (n,m);
    f[1,0]:=1;
    f[1,1]:=1;
    for i:=2 to n do
    begin
      for j:=0 to m-1 do
        f[i,0]:=f[i,0]+f[i-1,j];
      for j:=1 to m-1 do
        if i-j>=0 then
          f[i,j]:=f[i-1,j-1]
    end;
    for i:=0 to m-1 do
      sum:=sum+f[n,i];
    writeln (sum);
  close (input);
  close (output)
end.