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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>){
    val (n, m) = readLine()!!.split(" ").map { it.toInt() }
    val zyx = Array(m){ readLine()!!.split(" ").map { it.toInt() }.let { Triple(it[0], it[1], it[2]) }}

    val tree = UnionFind(n)
    zyx.forEach {
        tree.unite(it.first - 1, it.second - 1)
    }
    println(tree.size())
}

class UnionFind(n: Int) {

    private val parent = IntArray(n){ i -> i }

    fun root(x: Int): Int{
        if(parent[x] == x){
            return x
        }else{
            parent[x] = root(parent[x])
            return parent[x]
        }
    }

    fun unite(x: Int, y: Int){
        val rx = root(x)
        val ry = root(y)
        if(rx != ry){
            parent[rx] = ry
        }
    }

    fun size(): Int{
        return (parent.indices).map { root(it) }.distinct().size
    }
}