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.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 brg[][] = new int[m + 1][2];
		int gomi;
		for (int i = 1; i <= m; i++) {
			brg[i][0] = sc.nextInt();
			brg[i][1] = sc.nextInt();
			gomi = sc.nextInt();
		}
		int ans[] = Union(n, brg);
		for (int i = 1; i <= n; i++) {
			// System.out.println(ans[i]);
		}
		for (int i = 1; i <= n; i++) {
			// System.out.print(ans[i]+" ");
			ans[i] = Short(i, ans);
			System.out.println(ans[i]);
		}
		int kotae = 0;
		for (int i = 1; i <= n; i++) {
			if (ans[i] == i) {
				kotae++;
			}
		}
		System.out.println(kotae);

	}

	public static int[] Union(int node, int list[][]) {
		int ans[] = new int[node + 1];
		for (int i = 0; i <= node; i++) {
			ans[i] = i;
		}
//list[i][0]&list[i][1]
		for (int i = 1; i <= list.length - 1; i++) {

			ans[list[i][0]] = Math
					.min(ans[list[i][0]],
							Math.min(ans[list[i][1]],
									Math.min(list[i][0], list[i][1])));
			ans[list[i][1]] = Math
					.min(ans[list[i][0]],
							Math.min(ans[list[i][1]],
									Math.min(list[i][0], list[i][1])));

			ans[list[i][0]] =	Short(list[i][0],ans);
			ans[list[i][1]] =	Short(list[i][1],ans);
		}

		return ans;
	}

	static public int Short(int node, int list[]) {
		int next;
		if (list[node] == node) {
			return node;
		} else {
			next = list[node];
			list[node] = Short(next, list);
			return list[node];
		}
	}
}