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: Time Limit Exceeded)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;


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 numOfCards = Integer.parseInt(line1[0]);
    int numOfHints = Integer.parseInt(line1[1]);
    
    int[] groupArray = new int[numOfCards];
    int x;
    int y;
    int groupX;
    int groupY;
    int groupMaxNum = 1;
    int numOfGroup = numOfCards;
    
    for(int i=0; i<numOfHints; i++){
      String[] hint = br.readLine().split(" ");
      x = Integer.parseInt(hint[0])-1;
      y = Integer.parseInt(hint[1])-1;
      
      groupX = groupArray[x];
      groupY = groupArray[y];
      
      if(groupX == 0){
        if(groupY == 0){
          groupArray[x] = groupMaxNum;
          groupArray[y] = groupMaxNum;
          groupMaxNum++;
          numOfGroup--;
        }else{
          groupArray[x] = groupY;
          numOfGroup--;
        }
      }else{
        if(groupY == 0){
          groupArray[y] = groupX;
          numOfGroup--;
        }else if(groupX != groupY){
          numOfGroup--;
          for(int j=0; j<numOfCards; j++){
            if(groupArray[j] == groupY){
              groupArray[j] = groupX;
            }
          }
        }
      }
    }
    System.out.println(numOfGroup);
  }
}