#include <iostream>
#include <fstream>
#include <vector>
#include <stack>

using namespace std;

int n,m;
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;
    unsigned 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,i,c=0;
    for(i=0;i<m;i++)
    {
        f>>x>>y;
        x--;
        y--;
        graph[x].push_back(y);
        graph[y].push_back(x);
    }
    for(i=0;i<visited.size()&&i<n;i++)
        if(!visited[i])
    {
        c++;
        dfs(i);
    }
    g<<c;
    f.close();
    g.close();
    return 0;
}