Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
     
print(u.size(i))

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    print("{}の属するグループは{}人です。".format(i, u.size(i)))
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        
    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        
    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * (M-1)
B = [0] * (M-1)
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        # 木の高さを格納する（初期状態では0）
        """self.rank = [0] * (n + 1)"""

    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x
                # 木の高さが同じなら片方を1増やす
                """if self.rank[x] == self.rank[y]:
                    self.rank[x] += 1"""

    # 同じ集合に属するか判定
    def same_check(self, x, y):
        return self.find(x) == self.find(y)

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        # 木の高さを格納する（初期状態では0）
        """self.rank = [0] * (n + 1)"""

    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x
                # 木の高さが同じなら片方を1増やす
                """if self.rank[x] == self.rank[y]:
                    self.rank[x] += 1"""

    # 同じ集合に属するか判定
    def same_check(self, x, y):
        return self.find(x) == self.find(y)

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        # 木の高さを格納する（初期状態では0）
        """self.rank = [0] * (n + 1)"""

    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x
                # 木の高さが同じなら片方を1増やす
                """if self.rank[x] == self.rank[y]:
                    self.rank[x] += 1"""

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    print("{}の属するグループは{}人です。".format(i, u.size(i)))
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Buggy python submission (verdict: Runtime Error):
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

class UnionFind:
    def __init__(self, n):
        # 親要素のノード番号を格納。par[x] == xの時そのノードは根
        self.par = [-1 for i in range(n + 1)]
        # 木の高さを格納する（初期状態では0）
        """self.rank = [0] * (n + 1)"""

    # 検索
    # 根ならその番号を返す
    def find(self, x):
        if self.par[x] < 0:
            return x
        else:
            # 走査していく過程で親を書き換える
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # 併合
    def union(self, x, y):
        # 根を探す
        x = self.find(x)
        y = self.find(y)
        # 木の高さを比較し、低いほうから高いほうに辺を張る
        if x != y:
            if self.par[x] < self.par[y]:  # par<0の小さい方に合わせる
                self.par[y] += self.par[x]
                self.par[x] = y
            else:
                self.par[x] += self.par[y]
                self.par[y] = x
                # 木の高さが同じなら片方を1増やす
                """if self.rank[x] == self.rank[y]:
                    self.rank[x] += 1"""

    # 同じ集合に属するか判定
    def same_check(self, x, y):
        return self.find(x) == self.find(y)

    def size(self, x):
        return -self.par[self.find(x)]
    
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)

Fixed submission:
N, M = map(int, input().split())
A = [0] * M
B = [0] * M
for i in range(M):
    A[i], B[i] = map(int, input().split())

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

    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)]
    
u = UnionFind(N)
for i in range(M):
    u.union(A[i], B[i])
    
ans = 1
for i in range(1, N+1):
    ans = max(ans, u.size(i))
print(ans)