from collections import deque
import sys

sys.setrecursionlimit(10 ** 6)

class Dinic:
  def __init__(self, n, flow_limit):
    self.vertices = n
    self.flow_limit = flow_limit
    self.links = [[] for _ in range(n)]
    self.level = None
    self.progress = None

  def add_link(self, f, t, cap):
    from_id = len(self.links[f])
    to_id = len(self.links[t])
    if f == t:
      to_id += 1
    self.links[f].append([cap, t, to_id])
    self.links[t].append([0, f, from_id])

  def bfs(self, src, dst):
    level = [-1 for _ in range(self.vertices)]
    level[src] = 0
    dq = deque([src])
    while len(dq) > 0:
      cur = dq.popleft()
      for cap, nxt, _ in self.links[cur]:
        if cap > 0 and level[nxt] < 0:
          level[nxt] = level[cur] + 1
          dq.append(nxt)

    self.level = level
    return level[dst] != -1

  def dfs(self, cur, src, up):
    if cur == src:
      return up

    ans = 0
    lv_cur = self.level[cur]
    for i in range(self.progress[cur], len(self.links[cur])):
      self.progress[cur] += 1
      cap, nxt, rev = self.links[cur][i]
      if self.level[nxt] >= lv_cur or self.links[nxt][rev][0] == 0:
        continue

      d = self.dfs(nxt, src, min(up - ans, self.links[nxt][rev][0]))
      if d <= 0:
        continue

      self.links[cur][i][0] += d
      self.links[nxt][rev][0] -= d
      ans += d
      if ans == up:
        break

    return ans

  def max_flow(self, src, dst):
    ans = 0
    while ans < self.flow_limit:
      if not self.bfs(src, dst):
        break
      self.progress = [-1 for _ in range(self.vertices)]

      while ans < self.flow_limit:
        f = self.dfs(dst, src, self.flow_limit - ans)
        if f <= 0:
          break
        ans += f

    return ans

INF = 10 ** 13

n = int(input())

src = 2 * n
dst = src + 1
mf = Dinic(2 * n + 2, INF)

ans = 0
for u in range(n):
  b, c = map(int, input().split())
  ans += b + c
  ans += b + c # 何もしないの辺が余分にカットされるのであらかじめもらっておく
  mf.add_link(src, u, b + c)
  mf.add_link(u, dst, c)
  mf.add_link(src, u + n, b)
  mf.add_link(u + n, dst, b + c)
  mf.add_link(u, u + n, INF)

m = int(input())
for _ in range(m):
  d, e = map(int, input().split())
  mf.add_link(d, e + n, INF)

ans -= mf.max_flow(src, dst)
print(ans)