Problem:
Score : 500 points

Problem Statement

There are N cards placed face down in a row. On each card, an integer 1 or 2 is written.

Let A_i be the integer written on the i-th card.

Your objective is to guess A_1, A_2, ..., A_N correctly.

You know the following facts:

For each i = 1, 2, ..., M, the value A_{X_i} + A_{Y_i} + Z_i is an even number.

You are a magician and can use the following magic any number of times:

Magic: Choose one card and know the integer A_i written on it. The cost of using this magic is 1.

What is the minimum cost required to determine all of A_1, A_2, ..., A_N?

It is guaranteed that there is no contradiction in given input.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq M \leq 10^5

1 \leq X_i < Y_i \leq N

1 \leq Z_i \leq 100

The pairs (X_i, Y_i) are distinct.

There is no contradiction in input. (That is, there exist integers A_1, A_2, ..., A_N that satisfy the conditions.)

Input

Input is given from Standard Input in the following format:

N M
X_1 Y_1 Z_1
X_2 Y_2 Z_2
\vdots
X_M Y_M Z_M

Output

Print the minimum total cost required to determine all of A_1, A_2, ..., A_N.

Sample Input 1

3 1
1 2 1

Sample Output 1

2

You can determine all of A_1, A_2, A_3 by using the magic for the first and third cards.

Sample Input 2

6 5
1 2 1
2 3 2
1 3 3
4 5 4
5 6 5

Sample Output 2

2

Sample Input 3

100000 1
1 100000 100

Sample Output 3

99999

Solution in Python (3.8.2) (judge verdict: Accepted)

N,M=list(map(int,input().split()))
root=[i for i in range(N)]
height=[0]*N
def find(a):
   f=a
   if a==root[a]:
      return a
   while a!=root[a]:
      a=root[a]
   root[f]=a
   return a
def union(a,b):
   A=find(a)
   B=find(b)
   if A==B:
      return
   if height[A]>height[B]:
      root[B]=root[A]
   else:
      root[A]=root[B]
      if height[A]==height[B]:
         height[B]+=1

for i in range(M):
   a,b,c=map(int,input().split())
   a-=1;b-=1
   union(a,b)
l=[0]*N
for j in range(N):
   l[find(j)]+=1
print(N-l.count(0))