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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    big = max(a, b)
    small = min(a, b)
    
    if UF.par[big] == big:
        UF.par[big] = small
    else:
        UF.union(big, small)

for i in range(N):
    UF.find(i)
    
c = Counter(UF.par)

if len(c) == 1:
    print(n)
else:
    print(max(c.values()))
    

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))

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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    big = max(a, b)
    small = min(a, b)
    
    if UF.par[big] == big:
        UF.par[big] = small
    else:
        UF.union(big, small)

for i in range(N):
    UF.find(i)
    
c = Counter(UF.par)

if len(c.values()) == 1:
    print(n)
else:
    print(max(c.values()))

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))

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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    big = max(a, b)
    small = min(a, b)
    
    if UF.par[big] == big:
        UF.par[big] = small
    else:
        UF.union(big, small)

c = Counter(UF.par)
print(max(c.values()))

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))

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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n + 1)]
        self.rank = [0] * n
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    big = max(a, b)
    small = min(a, b)
    
    if UF.par[big] == big:
        UF.par[big] = small
    else:
        UF.union(big, small)
        
for i in range(N):
    _ = UF.find(i)

print(UF.par)

c = Counter(UF.par)
print(max(c.values()))

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))

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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    big = max(a, b)
    small = min(a, b)
    
    if UF.par[big] == big:
        UF.par[big] = small
    else:
        UF.union(big, small)
        
for i in range(N):
    _ = UF.find(i)

c = Counter(UF.par)
print(max(c.values()))

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))

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

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
            

N, M = map(int, input().split())
UF = UnionFind(N)
for i in range(M):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    UF.par[a] = b
    
for i in range(N):
    _ = UF.find(i)
    
c = Counter(UF.par)
print(max(c.values()))

Fixed submission:
from collections import Counter

class UnionFind():
    def __init__(self, n):
        self.par = [i for i in range(n)]
        self.rank = [0] * n
    
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]
    
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1
                
n, m = map(int, input().split())
uf = UnionFind(n)
for i in range(m):
    a, b = map(int, input().split())
    a -= 1
    b -= 1
    uf.union(a, b)

for i in range(n):
    uf.find(i)

c = Counter(uf.par)
print(max(c.values()))