using Yorukatsu046.Questions;
using Yorukatsu046.Extensions;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace Yorukatsu046.Questions
{
    /// <summary>
    /// ABC126 E
    /// </summary>
    public class QuestionE : AtCoderQuestionBase
    {
        public override IEnumerable<object> Solve(TextReader inputStream)
        {
            var nm = inputStream.ReadIntArray();
            var cards = nm[0];
            var hints = nm[1];
            var cardGroups = new UnionFindTree(cards);

            for (int i = 0; i < hints; i++)
            {
                var xyz = inputStream.ReadIntArray();
                var x = xyz[0] - 1;
                var y = xyz[1] - 1;
                cardGroups.Unite(x, y);
            }

            yield return cardGroups.Groups;
        }

        public class UnionFindTree
        {
            private UnionFindNode[] _nodes;
            public int Count => _nodes.Length;
            public int Groups { get; private set; }

            public UnionFindTree(int count)
            {
                _nodes = Enumerable.Range(0, count).Select(i => new UnionFindNode(i)).ToArray();
                Groups = _nodes.Length;
            }

            public void Unite(int index1, int index2)
            {
                var succeed = _nodes[index1].Unite(_nodes[index2]);
                if (succeed)
                {
                    Groups--;
                }
            }

            public bool IsInSameGroup(int index1, int index2) => _nodes[index1].IsInSameGroup(_nodes[index2]);
            public int GetGroupSizeOf(int index) => _nodes[index].GetGroupSize();

            private class UnionFindNode
            {
                private int _height;        // rootのときのみ有効
                private int _groupSize;     // 同上
                private UnionFindNode _parent;
                public int ID { get; }

                public UnionFindNode(int id)
                {
                    _height = 0;
                    _groupSize = 1;
                    _parent = this;
                    ID = id;
                }

                public UnionFindNode FindRoot()
                {
                    if (_parent != this) // not ref equals
                    {
                        var root = _parent.FindRoot();
                        _parent = root;
                    }

                    return _parent;
                }

                public int GetGroupSize() => FindRoot()._groupSize;

                public bool Unite(UnionFindNode other)
                {
                    var thisRoot = this.FindRoot();
                    var otherRoot = other.FindRoot();

                    if (thisRoot == otherRoot)
                    {
                        return false;
                    }

                    if (thisRoot._height < otherRoot._height)
                    {
                        thisRoot._parent = otherRoot;
                        otherRoot._groupSize += thisRoot._groupSize;
                        otherRoot._height = Math.Max(thisRoot._height + 1, otherRoot._height);
                        return true;
                    }
                    else
                    {
                        otherRoot._parent = thisRoot;
                        thisRoot._groupSize += otherRoot._groupSize;
                        thisRoot._height = Math.Max(otherRoot._height + 1, thisRoot._height);
                        return true;
                    }
                }

                public bool IsInSameGroup(UnionFindNode other) => this.FindRoot() == other.FindRoot();

                public override string ToString() => $"{ID} root:{FindRoot().ID}";
            }
        }

    }
}


namespace Yorukatsu046
{
    class Program
    {
        static void Main(string[] args)
        {
            IAtCoderQuestion question = new QuestionE();    // 問題に合わせて書き換え
            var answers = question.Solve(Console.In);
            foreach (var answer in answers)
            {
                Console.WriteLine(answer);
            }
        }
    }
}

#region Base Classes

namespace Yorukatsu046.Questions
{

    public interface IAtCoderQuestion
    {
        IEnumerable<object> Solve(string input);
        IEnumerable<object> Solve(TextReader inputStream);
    }

    public abstract class AtCoderQuestionBase : IAtCoderQuestion
    {
        public IEnumerable<object> Solve(string input)
        {
            var stream = new MemoryStream(Encoding.Unicode.GetBytes(input));
            var reader = new StreamReader(stream, Encoding.Unicode);

            return Solve(reader);
        }

        public abstract IEnumerable<object> Solve(TextReader inputStream);
    }

}

#endregion

#region Extensions

namespace Yorukatsu046.Extensions
{
    internal static class TextReaderExtensions
    {
        internal static int ReadInt(this TextReader reader) => int.Parse(ReadString(reader));
        internal static long ReadLong(this TextReader reader) => long.Parse(ReadString(reader));
        internal static double ReadDouble(this TextReader reader) => double.Parse(ReadString(reader));
        internal static string ReadString(this TextReader reader) => reader.ReadLine();

        internal static int[] ReadIntArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(int.Parse).ToArray();
        internal static long[] ReadLongArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(long.Parse).ToArray();
        internal static double[] ReadDoubleArray(this TextReader reader, char separator = ' ') => ReadStringArray(reader, separator).Select(double.Parse).ToArray();
        internal static string[] ReadStringArray(this TextReader reader, char separator = ' ') => reader.ReadLine().Split(separator);
    }
}

#endregion

Measured memory_bytes: 25440