Buggy python submission (verdict: Runtime Error):
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        root.size += 1
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
            else:
                root_b.parent = root_a



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)



Fixed submission:
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
                root_b.size == root_a.size
            else:
                root_b.parent = root_a
                root_a.size += root_b.size



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)

Buggy python submission (verdict: Runtime Error):
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        root.size += 1
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
            else:
                root_b.parent = root_a



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)



Fixed submission:
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
                root_b.size == root_a.size
            else:
                root_b.parent = root_a
                root_a.size += root_b.size



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)

Buggy python submission (verdict: Runtime Error):
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            root_a.parent = root_b



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)



Fixed submission:
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
                root_b.size == root_a.size
            else:
                root_b.parent = root_a
                root_a.size += root_b.size



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)

Buggy python submission (verdict: Runtime Error):
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        return Node.find_set(node.parent)

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            node_a.parent = root_b



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)



Fixed submission:
class Node():
    def __init__(self,index):
        self.index = index
        self.parent = self 
        self.size = 1

    @staticmethod
    def find_set(node):
        if node.parent == node:
            return node 
        root = Node.find_set(node.parent)
        node.parent = root
        return root

    @staticmethod
    def union(node_a,node_b):
        root_a = Node.find_set(node_a)
        root_b = Node.find_set(node_b)
        if root_a != root_b:
            if root_a.size < root_b.size:
                root_a.parent = root_b
                root_b.size == root_a.size
            else:
                root_b.parent = root_a
                root_a.size += root_b.size



if __name__ == "__main__":
    n,m = [int(val) for val in input().split()]
    
    persons = []
    count = []
    for i in range(n):
        persons.append(Node(i))
        count.append(0)
    
    for i in range(m):
        a,b = [int(val) for val in input().split()]
        if a > b:
            Node.union(persons[a-1],persons[b-1])
        else:
            Node.union(persons[b-1],persons[a-1])


    for idx,person in enumerate(persons):
        count[Node.find_set(person).index] += 1
    
    # print(count)
    result = max(count)
    print(result)