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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] line1 = br.readLine().split(" ");
    int numOfCard = Integer.parseInt(line1[0]);
    int numOfHint = Integer.parseInt(line1[1]);
    List<Set<Integer>> integerSetList = new ArrayList<>();
    
    int x;
    int y;
    boolean notFound;
    String[] data;
  
    data = br.readLine().split(" ");
    x = Integer.parseInt(data[0]);
    y = Integer.parseInt(data[1]);
    integerSetList.add(new HashSet<>());
    integerSetList.get(0).add(x);
    integerSetList.get(0).add(y);
    
    for(int i=1; i<numOfHint; i++){
      notFound = true;
      data = br.readLine().split(" ");
      x = Integer.parseInt(data[0]);
      y = Integer.parseInt(data[1]);
      for (Set<Integer> integer : integerSetList) {
        if (integer.contains(x) || integer.contains(y)) {
          integer.add(x);
          integer.add(y);
          notFound = false;
          break;
        }
      }
      if(notFound){
        Set<Integer> newSet = new HashSet<>();
        newSet.add(x);
        newSet.add(y);
        integerSetList.add(newSet);
      }
    }
    int hinted = 0;
    for(Set<Integer> set: integerSetList){
      hinted += set.size();
    }
    int numOfSeries = integerSetList.size();
    
    System.out.println(numOfCard - hinted + numOfSeries);
  }
}