import sys readline=sys.stdin.readline from collections import defaultdict def SCC(N,edges): start = [0] * (N + 1) elist = [0] * len(edges) for e in edges: start[e[0] + 1] += 1 for i in range(1, N + 1): start[i] += start[i - 1] counter = start[:] for e in edges: elist[counter[e[0]]] = e[1] counter[e[0]] += 1 N = N now_ord = group_num = 0 visited = [] low = [0] * N order = [-1] * N ids = [0] * N parent = [-1] * N stack = [] for i in range(N): if order[i] == -1: stack.append(i) stack.append(i) while stack: v = stack.pop() if order[v] == -1: low[v] = order[v] = now_ord now_ord += 1 visited.append(v) for i in range(start[v], start[v + 1]): to = elist[i] if order[to] == -1: stack.append(to) stack.append(to) parent[to] = v else: low[v] = min(low[v], order[to]) else: if low[v] == order[v]: while True: u = visited.pop() order[u] = N ids[u] = group_num if u == v: break group_num += 1 if parent[v] != -1: low[parent[v]] = min(low[parent[v]], low[v]) for i, x in enumerate(ids): ids[i] = group_num - 1 - x groups = [[] for _ in range(group_num)] for i, x in enumerate(ids): groups[x].append(i) return groups class TwoSAT: def __init__(self,N): self.N=N self.edges=[] def Add_Clause(self,i,f,j,g): assert 0<=i