#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
int n,m;
vector<vector<int> > graph;
vector<bool>visited;
void dfs(int vertex)
{
    if(vertex<0 || vertex>n-1) return;
    stack <int> s;
    int element,i;
    bool found;
    s.push(vertex);
    visited[vertex]=true;
    while(!s.empty())
    {
        element = s.top();
        found = false;
        for(i=0;i<graph[element].size() && !found;i++)
        {
            if(!visited[graph[element][i]])
                found=true;
        }

        if(found)
        {
            i--;
            s.push(graph[element][i]);
            visited[graph[element][i]]=true;
        }
        else s.pop();
    }
}
int main()
{
  f>>n>>m;
  graph.resize(n);
  visited.resize(n,false);
  int x,y;
  int nr=0;
  for(int i=0;i<m;i++)
  {
      f>>x>>y;
      x--;
      y--;
      graph[x].push_back(y);
      graph[y].push_back(x);
  }

  for(int i=0;i<visited.size()&&i<n;i++)
    if(!visited[i]) {nr++ ;dfs(i);}
g<<nr;
  return 0;
}