const v:array[0..10]of longint=(10,2,3,5,7,11,13,17,19,23,29);

var i,n,m,min:longint;
    sum:int64;

procedure Rezolva(pas:longint;prod:int64;sel:longint);
begin
  if pas < v[0] then
  begin
    Rezolva(pas+1,prod,sel);
    Rezolva(pas+1,prod*v[pas+1],sel+1);
  end
  else
  begin
    if sel > 0 then
    begin
      if (sel and 1) = 1 then
        prod := (n div prod)*(m div prod)
      else
        prod := -(n div prod)*(m div prod);

      sum := sum + prod;  writeln(prod);
    end;
  end;
end;

begin
  assign(input,'mins.in'); reset(input);
  assign(output,'mins.out'); rewrite(output);

  readln(n,m); dec(n); dec(m);

  min := n; if m < min then min := m;
  while v[v[0]] > min do dec(v[0]);

  sum := 0;
  Rezolva(0,1,0);


  writeln(n*m-sum);

  close(input);
  close(output);
end.