Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

D = [[-1] * N for _ in range(N)]
for i in range(N - 1):
  a, b = ab[i][0] - 1, ab[i][1] - 1
  a, b = min(a, b), max(a, b)
  D[a][b] = i

NL = [[] for _ in range(M)]
for i in range(M):
  x, y, r = uv[i][0] - 1, uv[i][1] - 1, uv[i][0] - 1
  L = T.dfs(x, y, r)
  n = L[0]
  t = 0
  for j in range(1, len(L)):
    m = L[j]
    x, y = min(n, m), max(n, m)
    t = t | (1 << D[x][y])
    n = m
  NL[i] = t
  

ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  D = [[0] * N for _ in range(N)]
  f = 0
  k = 0
  for j in range(M):
    if t & 1:
      f += 1
      k = k | NL[j]
    t >>= 1
  cnt = bin(k).count("1")
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))
print(ans - c)

Fixed submission:
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

D = [[-1] * N for _ in range(N)]
for i in range(N - 1):
  a, b = ab[i][0] - 1, ab[i][1] - 1
  a, b = min(a, b), max(a, b)
  D[a][b] = i

NL = [[] for _ in range(M)]
for i in range(M):
  x, y, r = uv[i][0] - 1, uv[i][1] - 1, uv[i][0] - 1
  L = T.dfs(x, y, r)
  n = L[0]
  t = 0
  for j in range(1, len(L)):
    m = L[j]
    x, y = min(n, m), max(n, m)
    t = t | (1 << D[x][y])
    n = m
  NL[i] = t
  

ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  f = 0
  k = 0
  for j in range(M):
    if t & 1:
      f += 1
      k = k | NL[j]
    t >>= 1
  cnt = bin(k).count("1")
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))
print(ans - c)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

NL = [[] for _ in range(M)]
for i in range(M):
  x, y, r = uv[i][0] - 1, uv[i][1] - 1, uv[i][0] - 1
  NL[i] = T.dfs(x, y, r)
ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  D = [[0] * N for _ in range(N)]
  cnt = 0
  f = 0
  for j in range(M):
    if t & 1:
      f += 1
      L = NL[j]
      n = L[0]
      for k in range(1, len(L)):
        m = L[k]
        x, y = min(n, m), max(n, m)
        if D[x][y] == 0:
          cnt += 1
        D[x][y] += 1
        n = m
    t >>= 1
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))

print(ans - c)

Fixed submission:
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

D = [[-1] * N for _ in range(N)]
for i in range(N - 1):
  a, b = ab[i][0] - 1, ab[i][1] - 1
  a, b = min(a, b), max(a, b)
  D[a][b] = i

NL = [[] for _ in range(M)]
for i in range(M):
  x, y, r = uv[i][0] - 1, uv[i][1] - 1, uv[i][0] - 1
  L = T.dfs(x, y, r)
  n = L[0]
  t = 0
  for j in range(1, len(L)):
    m = L[j]
    x, y = min(n, m), max(n, m)
    t = t | (1 << D[x][y])
    n = m
  NL[i] = t
  

ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  f = 0
  k = 0
  for j in range(M):
    if t & 1:
      f += 1
      k = k | NL[j]
    t >>= 1
  cnt = bin(k).count("1")
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))
print(ans - c)

Buggy python submission (verdict: Time Limit Exceeded):
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  D = [[0] * N for _ in range(N)]
  cnt = 0
  f = 0
  for j in range(M):
    if t & 1:
      f += 1
      x, y, r = uv[j][0] - 1, uv[j][1] - 1, uv[j][0] - 1
      L = T.dfs(x, y, r)
      n = L[0]
      for k in range(1, len(L)):
        m = L[k]
        x, y = min(n, m), max(n, m)
        if D[x][y] == 0:
          cnt += 1
        D[x][y] += 1
        n = m
    t >>= 1
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))

print(ans - c)

Fixed submission:
N = int(input())
ab = [list(map(int, input().split())) for _ in range(N - 1)]
M = int(input())
uv = [list(map(int, input().split())) for _ in range(M)]

class Tree:
  C, RL = {}, {}
  R, N, D, S, P = None, None, None, None, None
  def __init__(s, num):
    s.N = num
  def set(s, a, b):
    if a in s.C: s.C[a].append(b)
    else: s.C[a] = [b]
    if b in s.C: s.C[b].append(a)
    else: s.C[b] = [a]
  def dfs(s, x, y, r):
    if x == y:
      return [x]
    for i in s.C[x]:
      if i != r:
        t = s.dfs(i, y, x)
        if t != False:
          return [x] + t
    return False

T = Tree(N)
for a, b in ab:
  a -= 1
  b -= 1
  T.set(a, b)

D = [[-1] * N for _ in range(N)]
for i in range(N - 1):
  a, b = ab[i][0] - 1, ab[i][1] - 1
  a, b = min(a, b), max(a, b)
  D[a][b] = i

NL = [[] for _ in range(M)]
for i in range(M):
  x, y, r = uv[i][0] - 1, uv[i][1] - 1, uv[i][0] - 1
  L = T.dfs(x, y, r)
  n = L[0]
  t = 0
  for j in range(1, len(L)):
    m = L[j]
    x, y = min(n, m), max(n, m)
    t = t | (1 << D[x][y])
    n = m
  NL[i] = t
  

ans = 1 << (N - 1)
c = 0
for i in range(1, 1 << M):
  t = i
  f = 0
  k = 0
  for j in range(M):
    if t & 1:
      f += 1
      k = k | NL[j]
    t >>= 1
  cnt = bin(k).count("1")
  if f % 2 == 1:
    c += pow(2, (N - 1 - cnt))
  else:
    c -= pow(2, (N - 1 - cnt))
print(ans - c)