CF690C2 Brain Network (medium)

Further research on zombie thought processes yielded interesting results. As we know from the previous problem, the nervous system of a zombie consists of $ n $ brains and $ m $ brain connectors joining some pairs of brains together. It was observed that the intellectual abilities of a zombie depend mainly on the topology of its nervous system. More precisely, we define the distance between two brains $ u $ and $ v $ ( $ 1

The first line of the input contains two space-separated integers $ n $ and $ m $ ( $ 1

Print one number – the brain latency.