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.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        int N=sc.nextInt();
        int M=sc.nextInt();
        ArrayList<ArrayList<Integer>> list=new ArrayList<>();

        main:for(int i=0;i<M;i++){
            int x=sc.nextInt()-1;
            int y=sc.nextInt()-1;
            int z=sc.nextInt();
            for(int j=0;j<list.size();j++){
                if(list.get(j).contains(x)){
                    for(int k=0;k<list.size();k++) {
                        if(list.get(k).contains(y)){
                            if(j==k)continue main;
                            list.get(j).addAll(list.get(k));
                            list.remove(k);
                            continue main;
                        }
                    }

                }
                if(list.get(j).contains(y)){
                    for(int k=0;k<list.size();k++) {
                        if(list.get(k).contains(x)){
                            if(j==k)continue main;
                            list.get(j).addAll(list.get(k));
                            list.remove(k);
                            continue main;
                        }
                    }
                }
            }
           ArrayList<Integer> a=new ArrayList();
            a.add(x);
            a.add(y);
            list.add(a);
        }
        int result=0;
        test:
        for(int i=0;i<N;i++){
            for(int j=0;j<list.size();j++){
                if(list.get(j).contains(i)){
                    continue test;
                }
            }
            result++;
        }




        System.out.print(result+list.size());

    }
    static boolean isMonth(int a){
        return a>0&&a<13;
    }

}