Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))


Fixed submission:
import sys
sys.setrecursionlimit(1000000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000)
input = sys.stdin.readline

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))


Fixed submission:
import sys
sys.setrecursionlimit(1000000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))

Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(100000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))


Fixed submission:
import sys
sys.setrecursionlimit(1000000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))

Buggy python submission (verdict: Runtime Error):
def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))


Fixed submission:
import sys
sys.setrecursionlimit(1000000)

def MST(n, E):
    def par(m):
        if UF[m] == m:
            return m
        ret = par(UF[m])
        UF[m] = ret
        return ret
    
    UF = [i for i in range(n)]
    E = sorted(E, key=lambda x: x[2])
    ans = 0
    for i, j, d in E:
        if par(i) != par(j):
            ans += d
            UF[par(i)] = par(j)
    return ans

N = int(input())

X = []
for i in range(N):
    x, y = map(int, input().split())
    X.append((i, x, y))

F = []
Y = sorted(X, key = lambda x: x[1])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][1]-Y[i][1])))

Y = sorted(X, key = lambda x: x[2])
for i in range(len(Y)-1):
    F.append((Y[i][0], Y[i+1][0], abs(Y[i+1][2]-Y[i][2])))

print(MST(N, F))