#include <fstream>
#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <string.h>
#include <queue>
 
#define min(a,b) ((a<b)?a:b)
#define max(a,b) ((a<b)?b:a)
#define abs(a) ((a<0)?-a:a)
#define REP(i,a,b) \
	for (int i=a; i<=b; i++)
 
#define INF 1000001
 
using namespace std;
 

#ifndef TEST
ifstream fin ("dfs.in");
ofstream fout ("dfs.out");
#else
ifstream fin ("input.txt");
ofstream fout ("output.txt");
#endif
 
#define MAXN 100000

typedef long long ll;

int n,m,s=0;

vector<int> a[MAXN];

int r[MAXN];

void dfs(int x)
{
	if (r[x]) return;
	r[x] = 1;
	for (int i=0; i<a[x].size(); i++)
		if (r[ a[x][i] ] ==0) dfs(a[x][i]);
}

int main()
{
	fin>>n>>m;

	REP(i,0,n-1)
		r[i] = 0;
	REP(i,0,m-1)
	{
		int x,y;
		fin>>x>>y;
		x--;
		y--;
		a[x].push_back(y);
		a[y].push_back(x);
	}

	REP(i,0,n-1)
		if (r[i]==0)
		{
			s++;
			dfs(i);
		}

	fout<<s;
    return 0;
}