Buggy python submission (verdict: Runtime Error):
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(m):
    p = uni.find(i)
    t.add(p)
print(len(t))

Fixed submission:
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n-1)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(n):
    p = uni.find(i)
    t.add(p)
print(len(t))

Buggy python submission (verdict: Runtime Error):
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(m):
    p = uni.find(i)
    t.add(p)
print(len(t))

Fixed submission:
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n-1)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(n):
    p = uni.find(i)
    t.add(p)
print(len(t))

Buggy python submission (verdict: Runtime Error):
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n-1)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(m):
    p = uni.find(i)
    t.add(p)
print(len(t))

Fixed submission:
class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n+1)]
        self.rank = [0] * (n+1)

    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

    def same_check(self, x, y):
        return self.find(x) == self.find(y)
n,m=map(int,input().split())
uni = UnionFind(n-1)

for i in range(m):
    a,b,c=map(int,input().split())
    a-=1
    b-=1
    uni.union(a,b)
t = set([])
for i in range(n):
    p = uni.find(i)
    t.add(p)
print(len(t))