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>) {
    abc126e()
}

fun abc126e() {
    val (n, m) = readLine()!!.split(' ').map { it.toInt() }
    val xyzList = (1..m).map { readLine()!!.split(' ').map { it.toInt() - 1 } }

    val uf = UnionFind(n)
    xyzList.forEach { uf.unite(it[0], it[1]) }

    val answer = (0 until n).map { uf.root(it) }.distinct().count()

    println(answer)
}

private class UnionFind(initSize: Int) {
    private val parent = IntArray(initSize) { it }
    private val size = LongArray(initSize) { 1L }

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

        val xr = root(parent[x])
        parent[x] = xr
        return xr
    }

    fun unite(x: Int, y: Int) {
        val xr = root(x)
        val yr = root(y)
        if (xr == yr) return

        if (size[xr] >= size[yr]) {
            size[xr] += size[yr]
            parent[yr] = xr
        } else {
            size[yr] += size[xr]
            parent[xr] = yr
        }
    }

    fun isSame(x: Int, y: Int): Boolean = root(x) == root(y)

    fun size(x: Int): Long = size[root(x)]
}