Buggy python submission (verdict: Runtime Error):
import collections


class unionFind:
    parent = []
    count = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]
        self.count = [1]*N

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            self.count[x] = self.count[self.parent[x]]
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            self.count[y] += self.count[x]
            self.count[x] = self.count[y]
            return

    def getCount(self, x):
        x = self.root(x)
        return(self.count[x])


N, M = map(int, input().split())
G = unionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    G.unite(a, b)

ans = 1
for i in range(N):
    ans = max(ans, G.getCount(i))

print(ans)


Fixed submission:
import collections
import sys
sys.setrecursionlimit(10**6)
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(C[0][1])

Buggy python submission (verdict: Runtime Error):
import collections


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


N, M = map(int, input().split())
G = unionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    G.unite(a, b)

for i in range(N):
    G.root(i)
print(1)
# C = collections.Counter(G.parent).most_common()

# print(C[0][1])


Fixed submission:
import collections
import sys
sys.setrecursionlimit(10**6)
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(C[0][1])

Buggy python submission (verdict: Runtime Error):
import collections


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


N, M = map(int, input().split())
G = unionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(1)
# print(C[0][1])


Fixed submission:
import collections
import sys
sys.setrecursionlimit(10**6)
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(C[0][1])

Buggy python submission (verdict: Runtime Error):
import collections


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


N, M = map(int, input().split())
G = unionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    G.unite(a, b)


for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()


print(C[0][1])


Fixed submission:
import collections
import sys
sys.setrecursionlimit(10**6)
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(C[0][1])

Buggy python submission (verdict: Runtime Error):
import collections
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)
C = collections.Counter(G.parent).most_common()

print(C[0][1])


Fixed submission:
import collections
import sys
sys.setrecursionlimit(10**6)
N, M = map(int, input().split())
AB = [tuple(map(int, input().split())) for i in range(M)]


class unionFind:
    parent = []

    def __init__(self, N):
        self.parent = [i for i in range(N)]

    def root(self, x):
        if self.parent[x] == x:
            return(x)
        else:
            self.parent[x] = self.root(self.parent[x])
            return(self.parent[x])

    def same(self, x, y):
        x, y = x-1, y-1
        return(self.root(x) == self.root(y))

    def unite(self, x, y):
        x, y = x-1, y-1
        x = self.root(x)
        y = self.root(y)
        if x == y:
            return
        else:
            self.parent[x] = y
            return


G = unionFind(N)

for a, b in AB:
    G.unite(a, b)

for i in range(N):
    G.root(i)

C = collections.Counter(G.parent).most_common()

print(C[0][1])