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

    }
   /* for(i=0;i<s.size();i++)
    {g<<s.top()+1;s.pop();}*/
}
int main()
{
    int n,m;

    f>>n>>m;
    graph.resize(n);
    visited.resize(n,false);
    int x,y,i;
    for(i=0;i<m;i++)
       {
           f>>x>>y;
            x--;y--;
            graph[x].push_back(y);
            graph[y].push_back(x);
       }
       int k=0;
       for(i=0;i<visited.size()&&i<n;i++)
       {
           if(visited[i]==false)
           {dfs(i);k++;}
       }
g<<k<<'\n';
       return 0;
}