INF = float('inf') class Edge: def __init__(self, to, cap, rev): self.to = to self.cap = cap self.rev = rev class Dinic: def __init__(self, V): self.V = V self.size = [0] * V """:type : list[int]""" self.level = [] """:type : list[int]""" self.iterator = [] """:type : list[int]""" self.G = [[] for i in range(V)] """:type : list[list[Edge]]""" def add_edge(self, _from, to, cap): self.G[_from].append(Edge(to, cap, self.size[to])) self.G[to].append(Edge(_from, 0, self.size[_from])) self.size[_from] += 1 self.size[to] += 1 def bfs(self, s): from collections import deque level = [-1 for i in range(self.V)] level[s] = 0 q = deque([s]) while q: v = q.popleft() for u in self.G[v]: if u.cap > 0 > level[u.to]: level[u.to] = level[v] + 1 q.append(u.to) return level def dfs(self, v, t, f): if v == t: return f for i in range(self.iterator[v], self.size[v]): self.iterator[v] = i edge = self.G[v][i] if edge.cap > 0 and self.level[v] < self.level[edge.to]: d = self.dfs(edge.to, t, f if f < edge.cap else edge.cap) if d > 0: self.G[v][i].cap -= d self.G[edge.to][edge.rev].cap += d return d return 0 def max_flow(self, s, t): flow = 0 while True: self.level = self.bfs(s) if self.level[t] < 0: return flow self.iterator = [0 for i in range(self.V)] while True: f = self.dfs(s, t, float('inf')) if f == 0: break flow += f def solve(): N = int(input()) mf = Dinic(N * 2 + 2) s = 0 for i in range(N): b, c = list(map(int, input().split())) m = max(b, c) s += m mf.add_edge(0, i * 2 + 2, m - c) mf.add_edge(i * 2 + 2, i * 2 + 3, m) mf.add_edge(i * 2 + 3, 1, m - b) M = int(input()) for i in range(M): d, e = list(map(int, input().split())) mf.add_edge(d * 2 + 3, e * 2 + 2, INF) print(s - mf.max_flow(0, 1)) if __name__ == '__main__': solve()