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: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = ReadArrayInt();
            var N = input[0];
            var M = input[1];
            var clear = new bool[N + 1];
            var EO = new List<int[]>();
            var EEOO = new List<int[]>();
            for (int i = 0; i < M; i++)
            {
                input = ReadArrayInt();
                var X = input[0];
                var Y = input[1];
                var Z = input[2];
                if (Z % 2 != 0)
                {
                    EO.Add(new int[] { X, Y });
                }
                else
                {
                    EEOO.Add(new int[] { X, Y });
                }
            }
            var ans = 0;
            for (int i = 0; i < EO.Count(); i++)
            {
                var X = EO[i][0];
                var Y = EO[i][1];
                if (clear[X] && clear[Y]) continue;
                if (clear[X] || clear[Y])
                {
                    clear[X] = true;
                    clear[Y] = true;
                }
                else
                {
                    ans++;
                    clear[X] = true;
                    clear[Y] = true;
                }
            }
            for (int i = 0; i < EEOO.Count(); i++)
            {
                var X = EEOO[i][0];
                var Y = EEOO[i][1];
                if (clear[X] && clear[Y]) continue;
                if (clear[X] || clear[Y])
                {
                    clear[X] = true;
                    clear[Y] = true;
                }
                else
                {
                    ans++;
                    clear[X] = true;
                    clear[Y] = true;
                }
            }
            for (int i = 1; i <= N; i++)
            {
                if (!clear[i])
                {
                    ans++;
                }
            }

            Console.WriteLine(ans);
            Console.ReadLine();
        }

        static string Read() { return Console.ReadLine(); }
        static int ReadInt() { return int.Parse(Read()); }
        static long ReadLong() { return long.Parse(Read()); }
        static int[] ReadArrayInt() { return Read().Split(' ').Select(s => int.Parse(s)).ToArray(); }
        static long[] ReadArrayLong() { return Read().Split(' ').Select(s => long.Parse(s)).ToArray(); }
    }
}