#include<fstream>
#include<stack>
#include<vector>
#include<iostream>
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;
    bool found;
    s.push(vertex);
    visited[vertex]=true;
    while(!s.empty())
    {int i;
        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,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<n;i++)
        if(!visited[i])
            {
                DFS(i);
                nr++;
            }

    g<<nr;
    return 0;
}