def get_keypress_event_trigger_key(event: str) -> int:
    """Find the key number which triggers particular keypress event."""
    comparison_str = "e.which == "
    if comparison_str not in event:
        return -1
    comparison_start = event.index(comparison_str) + len(comparison_str)
    comparison_end = event.find(")", comparison_start)
    key = int(event[comparison_start:comparison_end])
    return key