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 Go (1.6) (judge verdict: Wrong Answer)

package main
import (
	"fmt"
	"sort"
)
func main(){ abc126e() }
func abc126e() {
	var n, m int
	fmt.Scanf("%d %d", &n, &m)

	// sort problems
	data := make(map[int]int, m)
	for i := 0; i < m; i++ {
		var a, b, dummy int
		fmt.Scanf("%d %d %d", &a, &b, &dummy)
		data[a] = b
	}

	var keys []int
	for k := range data {
		keys = append(keys, k)
	}
	sort.Ints(keys)

	ar := make([]int, n+1)
	currentIndex := 0
	for _, k := range keys {
		if ar[k] > 0 {
			ar[data[k]] = ar[k]
		} else if ar[data[k]] > 0 {
			ar[k] = ar[data[k]]
		} else {
			currentIndex++
			ar[k] = currentIndex
			ar[data[k]] = currentIndex
		}

		// ar := make([]int, n+1)
		// currentIndex := 0
		// for i := 0; i < m; i++ {
		// 	var a, b, dummy int
		// 	fmt.Scanf("%d %d %d", &a, &b, &dummy)
		// 	if ar[a] > 0 {
		// 		ar[b] = ar[a]
		// 	} else if ar[b] > 0 {
		// 		ar[a] = ar[b]
		// 	} else {
		// 		currentIndex++
		// 		ar[a] = currentIndex
		// 		ar[b] = currentIndex
		// 	}
	}

	ans := currentIndex
	for i := 1; i <= n; i++ {
		if ar[i] == 0 {
			ans++
		}
	}
	fmt.Printf("%d", ans)
}