Buggy python submission (verdict: Runtime Error):
import numpy as np
from scipy.sparse.csgraph import minimum_spanning_tree
from scipy.sparse import csr_matrix, coo_matrix, lil_matrix

n=int(input())
l=[]
for i in range(n):
    l.append([i]+list(map(int,input().split())))
g = [[0 for j in range(n)]for i in range(n)]
l.sort(key=lambda x: x[1])
for i in range(n-1):
    p=l[i][0]
    q=l[i+1][0]
    if p<q:p,q=q,p
    g[p][q]= abs(l[i+1][1]-l[i][1])
l.sort(key=lambda x: x[2])
for i in range(n-1):
    p=l[i][0]
    q=l[i+1][0]
    if p<q:p,q=q,p
    if g[p][q] != 0:
        g[p][q] = min(g[l[i][0]][l[i+1][0]],abs(l[i+1][2]-l[i][2]))
    else:
        g[p][q] = abs(l[i+1][2]-l[i][2])
mst = minimum_spanning_tree(g)
print(int(mst.sum()))



Fixed submission:
n=int(input())
l=[]
for i in range(n):
    l.append([i]+list(map(int,input().split())))
g = []
l.sort(key=lambda x: x[1])
for i in range(n-1):
    g.append([l[i][0],l[i+1][0],abs(l[i][1]-l[i+1][1])])
l.sort(key=lambda x: x[2])
for i in range(n-1):
    g.append([l[i][0],l[i+1][0],abs(l[i][2]-l[i+1][2])])

class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())

def minimum_spanning_tree(g,n):
#g=list、「始点、終点、辺の重み」
#n=頂点数
    g.sort(key=lambda x: x[2])
    uf = UnionFind(n)
    ret = 0
    for sg in g:
        a,b,c = sg[0],sg[1],sg[2]
        if not uf.same(a,b):
            uf.union(a,b)
            ret += c
    return ret

print(minimum_spanning_tree(g,n))

Buggy python submission (verdict: Runtime Error):
import numpy as np
from scipy.sparse.csgraph import minimum_spanning_tree
from scipy.sparse import csr_matrix, coo_matrix, lil_matrix

n=int(input())
l=[]
INF = 10**10
for i in range(n):
    l.append([i]+list(map(int,input().split())))
g = [[INF for j in range(n)]for i in range(n)]
l.sort(key=lambda x: x[1])
for i in range(n-1):
    p=l[i][0]
    q=l[i+1][0]
    if p<q:p,q=q,p
    g[p][q]= abs(l[i+1][1]-l[i][1])
l.sort(key=lambda x: x[2])
for i in range(n-1):
    p=l[i][0]
    q=l[i+1][0]
    if p<q:p,q=q,p
    g[p][q] = min(g[l[i][0]][l[i+1][0]],abs(l[i+1][2]-l[i][2]))
mst = minimum_spanning_tree(g)
print(int(mst.sum()))



Fixed submission:
n=int(input())
l=[]
for i in range(n):
    l.append([i]+list(map(int,input().split())))
g = []
l.sort(key=lambda x: x[1])
for i in range(n-1):
    g.append([l[i][0],l[i+1][0],abs(l[i][1]-l[i+1][1])])
l.sort(key=lambda x: x[2])
for i in range(n-1):
    g.append([l[i][0],l[i+1][0],abs(l[i][2]-l[i+1][2])])

class UnionFind():
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)

        if x == y:
            return

        if self.parents[x] > self.parents[y]:
            x, y = y, x

        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())

def minimum_spanning_tree(g,n):
#g=list、「始点、終点、辺の重み」
#n=頂点数
    g.sort(key=lambda x: x[2])
    uf = UnionFind(n)
    ret = 0
    for sg in g:
        a,b,c = sg[0],sg[1],sg[2]
        if not uf.same(a,b):
            uf.union(a,b)
            ret += c
    return ret

print(minimum_spanning_tree(g,n))