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.Arrays;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();

        int[] uf = new int[N];
        Arrays.fill(uf,-1);

        for (int i = 0; i < M; i++) {
            int x = sc.nextInt()-1;
            int y = sc.nextInt()-1;
            int z = sc.nextInt();

            connect(x,y,uf);

        }

        int count =0;
        for(int leader : uf) if(leader==-1) count++;
        System.out.println(count);
    }

    static    private int findLeader(int i ,int[] uf){
        if (uf[i] ==-1) return i;
        int leader = findLeader(uf[i], uf);
        uf[i] = leader;
        return leader;
    }
    static  private void connect(int i ,int j, int[] uf){
        int leader1 = findLeader(i,uf);
        int leader2 = findLeader(j,uf);
        if(leader1 == leader2) return;

        if(leader1 < leader2){
            uf[leader2] = leader1;
        }


    }
}