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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;

public class CSharp
{
    public static void Main()
    {
        Kyopuro chokudai = new Kyopuro();
        chokudai.AtCoder();
    }
}

public class Kyopuro
{
    int n, m;
    int[] x, y, z;

    public void AtCoder()
    {
        string[] input;
        input = Console.ReadLine().Split(' ');
        n = int.Parse(input[0]);
        m = int.Parse(input[1]);

        x = new int[m];
        y = new int[m];
        z = new int[m];

        for (int i=0; i<m; i++)
        {
            input = Console.ReadLine().Split(' ');
            x[i] = int.Parse(input[0]) - 1;
            y[i] = int.Parse(input[1]) - 1;
            z[i] = int.Parse(input[2]);
        }

        var uf = new UnionFind(n);
        for(int i=0; i<m; i++)
        {
            uf.Union(x[i], y[i]);
        }
        int[] t = new int[n];
        int u = 0;
        int ans = 0;
        for(int i=0; i<n; i++)
        {
            u = uf.Find(i);
            if(t[u] == 0)
            {
                t[u]++;
                ans++;
            }
        }
        Console.WriteLine(ans);

    }


    

    public static void DebugWL(object x) { System.Diagnostics.Debug.WriteLine(x); }
}

// UnionFind(int n)
// n: the number of nodes
// int Find(int node): return the parent
// void Union(int node, int node)

public class UnionFind
{
    int[] par;
    int n;
    public UnionFind(int t)
    {
        n = t;
        par = new int[n];
        for (int i = 0; i < n; i++)
        {
            par[i] = i;
        }
    }

    public int Find(int x)
    {
        if (par[x] == x) return x;
        else
        {
            par[x] = Find(par[x]);
            return par[x];
        }
    }

    public void Union(int x, int y)
    {
        x = Find(x);
        y = Find(y);
        if (x == y) return;
        else par[x] = y;
    }
}