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.Iterator;

public class Main{
  public static void main(String args[]){
    int n, m;
    ArrayList<int[]> input = new ArrayList<>();
    
    try {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String str = reader.readLine();
        String[] tmp = str.split(" ");
        n = Integer.parseInt(tmp[0]);
        m = Integer.parseInt(tmp[1]);
        String str2;
        while((str2 = reader.readLine())!=null){
            String[] tmp2 = str2.split(" ");
          	int nums[] = new int[2];
            nums[0] = Integer.parseInt(tmp2[0]);
            nums[1] = Integer.parseInt(tmp2[1]);
          	input.add(nums);
        }
      	System.out.println(count(input));
    } catch (IOException e) {
                e.printStackTrace();
    }
  }
  
  public static int count(ArrayList<int[]> list){
    int result = 0;
  	for(int[] val : list){
      	//print(list);
    	if(val[0] != 0 && val[1] == 0){
          rm(list,val[0]);
        }
		if(val[0] == 0 && val[1] != 0){
          rm(list,val[1]);
        }
      	if(val[0] != 0 && val[1] != 0){
          rm(list,val[0]);
          rm(list,val[1]);
          result++;
        }
      //print(list);
    }
    return result;
  }
    
    
  public static void rm(ArrayList<int[]> list, int target){
	for(int[] val : list){
      if(val[0] == target){
          val[0] = 0;
      }
      if(val[1] == target){
          val[1] = 0;
      }
    }
  }
  
  public static void print(ArrayList<int[]> list){
	for(int[] val : list){
		System.out.println(val[0] + ":" + val[1]);
    }
    System.out.println("----------------------------");
  }
}