VAR
  N, M, I : LongInt;
  Prim : ARRAY[1..10000] OF LongInt;
  Res : ARRAY[1..10000] OF LongInt;
  PrimC, P : LongInt;
  FUNCTION Simple(C : LongInt) : Boolean;
  VAR
    I : LongInt;
  BEGIN
    Simple := False;
    FOR I := 2 TO Round(Sqrt(N)) DO
      IF C MOD I = 0 THEN Exit;
    Simple := True;
  END;
BEGIN
  FillChar(Res, SizeOf(Res), 0);
  FillChar(Prim, SizeOf(Prim), 0);
  Read(N, M);
  PrimC := 0;
  IF N = 0 THEN BEGIN Write('0'); Halt; END;
  FOR I := 2 TO N DO
    IF Simple(I) THEN
      BEGIN
        Inc(PrimC);
        Prim[PrimC] := I;
      END;
  FOR I := 1 TO PrimC DO
    BEGIN
      P := Prim[I];
      REPEAT
        Res[I] := Res[I]+(N DIV P)-(M DIV P)-(((N-M) DIV P));
        P := P*Prim[I];
      UNTIL N DIV P = 0
    END;
  P := 0;
  FOR I := 1 TO PrimC DO
    IF Res[I] <> 0 THEN Inc(P);
  Write(P);
END.

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