Buggy python submission (verdict: Runtime Error):
import numpy as np
from scipy.sparse import *

U = 10
N = int(input())
XY = np.array([input().split() for _ in range(N)], dtype=np.int32)

graph = csr_matrix((np.ones(N,dtype=np.bool), (XY[:,0], U + XY[:,1])), (2*U+1, 2*U+1))
_, component = csgraph.connected_components(graph)

X_cnt = np.bincount(component[:U+1], minlength = 2*U+2)
Y_cnt = np.bincount(component[U+1:], minlength = 2*U+2)
pts_cnt = np.bincount(component[XY[:,0]], minlength = 2*U+2)
answer = (X_cnt * Y_cnt - pts_cnt).sum()
print(answer)


Fixed submission:
# (x,a), (x,b) → (s,a)と(t,b)は同値になる → aとbを同一視
# 連結成分を作る
N = int(input())
U = 10 ** 5
root_x = [None] * (U+1)
root_y = [None] * (U+1)
size_x = [0] * (U+1) # 連結成分のxの個数
size_y = [0] * (U+1) # 連結成分のyの個数
cnt_x = [0] * (U+1) # 生成時に登場した点
cnt_y = [0] * (U+1) # 生成時に登場した点
x_to_y = [None] * (U+1)
y_to_x = [None] * (U+1)

def find_root(root,size,x):
  y = root[x]
  if y is None:
    root[x] = x
    size[x] = 1
    return x
  if x == y:
    return y
  z = find_root(root,size,y)
  root[x] = z
  return z

def merge(root,size,cnt,x,y):
  rx = find_root(root,size,x)
  ry = find_root(root,size,y)
  if rx == ry:
    return
  sx = size[rx]
  sy = size[ry]
  if sx > sy:
    root[ry] = rx
    size[rx] += sy
    cnt[rx] += cnt[ry]
  else:
    root[rx] = ry
    size[ry] += sx
    cnt[ry] += cnt[rx]
  return

for _ in range(N):
  x,y = map(int,input().split())
  rx = find_root(root_x,size_x,x)
  ry = find_root(root_y,size_y,y)
  cnt_x[rx] += 1
  cnt_y[ry] += 1
  if x_to_y[rx] is None:
    x_to_y[rx] = ry
  if y_to_x[ry] is None:
    y_to_x[ry] = rx
  merge(root_y, size_y, cnt_y, x_to_y[rx], ry)
  merge(root_x, size_x, cnt_x, y_to_x[ry], rx)
  x_to_y[root_x[rx]] = root_y[ry]
  y_to_x[root_y[ry]] = root_x[rx]

  
answer = 0

for x in range(1,U+1):
  if root_x[x] is None:
    continue
  rx = find_root(root_x,size_x,x)
  if x != rx:
    continue
  y = x_to_y[x]
  ry = find_root(root_y,size_y,y)
  sx = size_x[rx]
  sy = size_y[ry]
  cnt = cnt_x[rx]
  answer += (sx * sy - cnt)
print(answer)

Buggy python submission (verdict: Runtime Error):
import numpy as np
from scipy.sparse import *

U = 10
N = int(input())
XY = np.array([input().split() for _ in range(N)], dtype=np.int32)

graph = csr_matrix((np.ones(N,dtype=np.bool), (XY[:,0], U + XY[:,1])), (2*U+1, 2*U+1))
_, component = csgraph.connected_components(graph)

X_cnt = np.bincount(component[:U+1], minlength = U+2)
Y_cnt = np.bincount(component[U+1:], minlength = U+2)
pts_cnt = np.bincount(component[XY[:,0]], minlength = U+2)
answer = (X_cnt * Y_cnt - pts_cnt).sum()
print(answer)

Fixed submission:
# (x,a), (x,b) → (s,a)と(t,b)は同値になる → aとbを同一視
# 連結成分を作る
N = int(input())
U = 10 ** 5
root_x = [None] * (U+1)
root_y = [None] * (U+1)
size_x = [0] * (U+1) # 連結成分のxの個数
size_y = [0] * (U+1) # 連結成分のyの個数
cnt_x = [0] * (U+1) # 生成時に登場した点
cnt_y = [0] * (U+1) # 生成時に登場した点
x_to_y = [None] * (U+1)
y_to_x = [None] * (U+1)

def find_root(root,size,x):
  y = root[x]
  if y is None:
    root[x] = x
    size[x] = 1
    return x
  if x == y:
    return y
  z = find_root(root,size,y)
  root[x] = z
  return z

def merge(root,size,cnt,x,y):
  rx = find_root(root,size,x)
  ry = find_root(root,size,y)
  if rx == ry:
    return
  sx = size[rx]
  sy = size[ry]
  if sx > sy:
    root[ry] = rx
    size[rx] += sy
    cnt[rx] += cnt[ry]
  else:
    root[rx] = ry
    size[ry] += sx
    cnt[ry] += cnt[rx]
  return

for _ in range(N):
  x,y = map(int,input().split())
  rx = find_root(root_x,size_x,x)
  ry = find_root(root_y,size_y,y)
  cnt_x[rx] += 1
  cnt_y[ry] += 1
  if x_to_y[rx] is None:
    x_to_y[rx] = ry
  if y_to_x[ry] is None:
    y_to_x[ry] = rx
  merge(root_y, size_y, cnt_y, x_to_y[rx], ry)
  merge(root_x, size_x, cnt_x, y_to_x[ry], rx)
  x_to_y[root_x[rx]] = root_y[ry]
  y_to_x[root_y[ry]] = root_x[rx]

  
answer = 0

for x in range(1,U+1):
  if root_x[x] is None:
    continue
  rx = find_root(root_x,size_x,x)
  if x != rx:
    continue
  y = x_to_y[x]
  ry = find_root(root_y,size_y,y)
  sx = size_x[rx]
  sy = size_y[ry]
  cnt = cnt_x[rx]
  answer += (sx * sy - cnt)
print(answer)