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: Time Limit Exceeded)

import java.util.*
fun solve(matrix: MutableMap<Int, MutableMap<Int,Int>>,num_nodes:Int) : Int {

    val visited: Array<Boolean> = Array(num_nodes) {
        false
    }
    var count = 0

    while(matrix.keys.any { visited[it - 1] == false }) {
        count++
        val index_stack: Stack<Int> = Stack()
        val root_index = visited.indices.first {visited[it] == false }
        
        visited[root_index] = true
        index_stack.push(root_index + 1)

        while(! index_stack.isEmpty()) {
            val index = index_stack.pop()
            matrix[index]?.forEach { 
                if(visited[it.key - 1] == false) {
                    index_stack.push(it.key)
                     
                    visited[it.key - 1] = true                    
                }
            }
        }
    }


    return count + visited.filter {!it}.size 
}
fun main(args:Array<String>) {
    val (N, M) = readLine()!!.split(" ").map(String::toInt)
     val graph:MutableMap<Int, MutableMap<Int,Int>> = mutableMapOf()
     0.until(M).forEach {
        val (x,y,z) = readLine()!!.split(" ").map(String::toInt)
        if(!graph.contains(x)) {
            graph.set(x, mutableMapOf())
        }
        if(!graph.contains(y)) {
            graph.set(y, mutableMapOf())
        }
        graph[x]!!.set(y, z)
        graph[y]!!.set(x, z)
    }
    solve(graph,N).run(::println)
}