using System;
using AtCoder;

class Program
{
    static void Main()
    {
        var tokens = Console.In.ReadToEnd()
            .Split((char[])null, StringSplitOptions.RemoveEmptyEntries);
        int p = 0;
        int n = int.Parse(tokens[p++]);
        int m = int.Parse(tokens[p++]);
        var d = new Dsu(n);
        for (int i = 0; i < m; i++)
        {
            int u = int.Parse(tokens[p++]);
            int v = int.Parse(tokens[p++]);
            d.Merge(u, v);
        }
        int c = 0;
        for (int i = 0; i < n; i++)
        {
            if (d.Leader(i) == i) c++;
        }
        Console.WriteLine(c);
    }
}