CF1386C Joker

Joker returns to Gotham City to execute another evil plan. In Gotham City, there are $ N $ street junctions (numbered from $ 1 $ to $ N $ ) and $ M $ streets (numbered from $ 1 $ to $ M $ ). Each street connects two distinct junctions, and two junctions are connected by at most one street. For his evil plan, Joker needs to use an odd number of streets that together form a cycle. That is, for a junction $ S $ and an even positive integer $ k $ , there is a sequence of junctions $ S, s_1, \ldots, s_k, S $ such that there are streets connecting (a) $ S $ and $ s_1 $ , (b) $ s_k $ and $ S $ , and (c) $ s_{i-1} $ and $ s_i $ for each $ i = 2, \ldots, k $ . However, the police are controlling the streets of Gotham City. On each day $ i $ , they monitor a different subset of all streets with consecutive numbers $ j $ : $ l_i \leq j \leq r_i $ . These monitored streets cannot be a part of Joker's plan, of course. Unfortunately for the police, Joker has spies within the Gotham City Police Department; they tell him which streets are monitored on which day. Now Joker wants to find out, for some given number of days, whether he can execute his evil plan. On such a day there must be a cycle of streets, consisting of an odd number of streets which are not monitored on that day.

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The graph in the example test: