how to designate wakeup msec by HAL_RTCEx_SetWakeUpTimer()

[curiae]

Hello,

Now I mean to generate periodic wake-up by HAL_RTCEx_SetWakeUpTimer().

But I'm not sure about arguments WakeUpCounter and WakeUpClock.

For realize 50msec wake-up what value should be set to  WakeUpCounter and which RTCCLK_DIV should be selected.

Thanks