With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: The 12-hour clock does not divide the day into a.m. and p.m.
text_B: The 12-hour clock is a time convention in which the 24 hours of the day are divided into two periods  : a.m. -LRB- from the Latin , ante meridiem , meaning before midday -RRB- and p.m. -LRB- post meridiem , meaning past midday -RRB- .. Latin. Latin. Each period consists of 12 hours numbered  : 12 -LRB- acting as zero -RRB- , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , and 11 .. The 24 hour / day cycle starts at 12 midnight -LRB- often indicated as 12 a.m. -RRB- , runs through 12 noon -LRB- often indicated as 12 p.m. -RRB- , and continues to the midnight at the end of the day .. The 12-hour clock was developed over time from the mid-second millennium BC to the 16th century AD .. Anno Domini. Anno Domini
related.