#include<iostream>
#include<fstream>
#include<vector>
#include<stack>
using namespace std;
int n,m;
vector< vector<int> >graph;
vector<bool> visited;
void dfs(int vertex)
{
    if(vertex<0 || vertex>=n) 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()
{   ifstream f("in.txt");
    ofstream g("out.txt");
    int x,y,counter=0;
    f>>n>>m;
    graph.resize(n);
    visited.resize(n,false);
    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++)
        if(!visited[i])
    {
        dfs(i);
        counter++;
    }
    g<<counter;
}