#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
vector<vector<int> > graph;
vector<bool> visited;
int n,m;
int nr_comp_conex=0;

void DFS(int vertex)
{if(vertex<0||vertex>n-1)
{return;}
vector<int> s;
int element;
unsigned int i;
bool found;
s.push_back(vertex);
visited[vertex]=true;
while(!s.empty())
{element=s.back();
found=false;
for(i=0;i<graph[element].size()&&!found;i++)
{if(!visited[graph[element][i]])
{found=true;}}
if(found)
{i--;
s.push_back(graph[element][i]);
visited[graph[element][i]]=true;}
else{s.pop_back();}}}

int main()
{f>>n>>m;
graph.resize(n);
visited.resize(n,0);
int n1,n2,i;
for(i=0;i<m;i++)
{f>>n1>>n2;
n1--;
n2--;
graph[n1].push_back(n2);
graph[n2].push_back(n1);}
for(i=0;i<visited.size()&&i<n;i++){
if(!visited[i])
{DFS(i);
nr_comp_conex++;}}
g<<nr_comp_conex;
return 0;}