Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import lil_matrix

N = int(input())
edge = lil_matrix((N,N))

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]
for key in [itemgetter(1), itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1,i2] = d

edge = edge.tocsr()

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(edge, overwrite = True).astype(int)
answer = tree.sum()
print(answer)

Fixed submission:
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import csr_matrix
import numpy as np

N = int(input())

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]

edge = [set() for _ in range(N)]
for key in [itemgetter(1),itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1].add((i2,d))
    
# csr形式に直す
indptr = []
indrow = []
value = []
ptr = 0
for i in range(N):
  indptr.append(ptr)
  for j,v in edge[i]:
    indrow.append(j)
    value.append(v)
    ptr += 1
indptr.append(ptr)
value = np.array(value,dtype=int)
graph = csr_matrix((value,indrow,indptr),shape=(N,N))

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(graph, overwrite = True).astype(int)
answer = tree.sum()
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import lil_matrix

N = int(input())
edge = lil_matrix((N,N))

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]
for key in [itemgetter(1), itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1,i2] = d

edge = edge.tocsr()

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(edge, overwrite = True).astype(int)
answer = tree.sum()
print(answer)

Fixed submission:
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import csr_matrix
import numpy as np

N = int(input())

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]

edge = [set() for _ in range(N)]
for key in [itemgetter(1),itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1].add((i2,d))
    
# csr形式に直す
indptr = []
indrow = []
value = []
ptr = 0
for i in range(N):
  indptr.append(ptr)
  for j,v in edge[i]:
    indrow.append(j)
    value.append(v)
    ptr += 1
indptr.append(ptr)
value = np.array(value,dtype=int)
graph = csr_matrix((value,indrow,indptr),shape=(N,N))

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(graph, overwrite = True).astype(int)
answer = tree.sum()
print(answer)

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import lil_matrix

N = int(input())
edge = lil_matrix((N,N))

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]
for key in [itemgetter(1), itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1,i2] = d
    edge[i2,i1] = d

edge = edge.tocsc()

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(edge, overwrite = True).astype(int)
answer = tree.sum()
print(answer)

Fixed submission:
import sys
input = sys.stdin.readline
from operator import itemgetter
from scipy.sparse import csr_matrix
import numpy as np

N = int(input())

XY = [[i] + [int(x) for x in input().split()] for i in range(N)]

edge = [set() for _ in range(N)]
for key in [itemgetter(1),itemgetter(2)]:
  XY.sort(key = key)
  for i in range(N-1):
    i1,x1,y1 = XY[i]
    i2,x2,y2 = XY[i+1]
    d = min(abs(x1-x2),abs(y1-y2))
    edge[i1].add((i2,d))
    
# csr形式に直す
indptr = []
indrow = []
value = []
ptr = 0
for i in range(N):
  indptr.append(ptr)
  for j,v in edge[i]:
    indrow.append(j)
    value.append(v)
    ptr += 1
indptr.append(ptr)
value = np.array(value,dtype=int)
graph = csr_matrix((value,indrow,indptr),shape=(N,N))

# 最小全域木
from scipy.sparse.csgraph import minimum_spanning_tree
tree = minimum_spanning_tree(graph, overwrite = True).astype(int)
answer = tree.sum()
print(answer)