모든 U 정점의 차수가 2인 이분 그래프에서 완전 매칭별 간선 가중치 곱의 합을 998244353으로 나눈 나머지를 구한다.
어려움8그래프DFS수학조합론아직 제출이 없습니다시간 제한1초메모리 제한512 MBIn the mathematical discipline of graph theory, a bipartite graph is an undirected graph whose vertices can be divided into two disjoint sets U and V such that every edge connects some vertex in U to some vertex in V. The vertex sets U and V are both independent sets, and are usually called the parts of the graph. Equivalently, a bipartite graph is a graph that does not contain any odd-length cycles. A matching in a graph is a set of edges without common vertices. A perfect matching is a matching such that each vertex is covered by an edge from the matching.
Little Q misunderstood the definition of bipartite graph. He thinks the size of U is equal to the size of V, and for each vertex p in U, there are exactly two edges from p. Based on such weighted graph, he defines the weight of a perfect matching as the product of weights of all the edges included in the matching, and the weight of a graph as the sum of all the perfect matchings' weights.
Your task is to write a program to compute the weight of a weighted graph made by Little Q.
The first line of the input contains an integer n denoting the size of U (1≤n≤3⋅105). The vertices in U and V are labeled separately by the integers 1,2,…,n.
In the next n lines, the i-th line contains four integers v_i,1, w_i,1, v_i,2 and w_i,2 which mean that there is an edge between U_i and V_v_i,1 with weight w_i,1, and there is another edge between U_i and V_v_i,2 with weight w_i,2 (1≤v_i,j≤n, 1≤w_i,j≤109).
It is guaranteed that the given graph has at least one perfect matching, and there is at most one edge between every pair of vertices.
Print a single line containing a single integer: the weight of the given graph. Since the answer may be very large, print it modulo 998,244,353.