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: Runtime Error)

import java.util.*;
class UnionFind{
  int length;
  int[] parent;
  int[] deep;
  int rootX,rootY;
  public UnionFind(int length){
    this.length=length;
    parent=new int[length];
    for(int i=0;i<=length;i++){
      parent[i]=i;
    }
    deep=new int[length];
  }
  public int getRoot(int x){
    if(parent[x]==x){
      return x;
    }else{
      return parent[x]=getRoot(x);
    }
  }
  public void makeSame(int x,int y){
    rootX=getRoot(x);
    rootY=getRoot(y);
      if(rootX==rootY){
        return;
      }else if(deep[rootX]>deep[rootY]){
        parent[rootY]=parent[rootX];
      }else{
        parent[rootX]=parent[rootY];
        if(deep[rootX]==deep[rootY])deep[rootY]++;
      }
    length--;
  }
  public boolean isSame(int x,int y){
    return getRoot(x)==getRoot(y);
  }
}
public class Main{
  public static void main(String[] args){
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    UnionFind uf=new UnionFind(n);
    int m=sc.nextInt();
    for(int i=0;i<m;i++){
      uf.makeSame(sc.nextInt()-1,sc.nextInt()-1);
      sc.nextInt();
    }
    System.out.println(uf.length);
  }
}