#include <iostream>
#include <utility>
#include <fstream>
#include <vector>
#include <unordered_map>
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");
int p[100003],rang[100003];
void FormeazaMutlime(int x)
{
    p[x] = x;
    rang[x] = 0;
}
int GasesteMultime(int x)
{
    int tata =x,y;
    while(p[tata] !=tata)
        tata = p[tata];
    while(p[x]!=x)
        y = p[x], p[x] = tata, x =y;
    return tata;
}
void Uneste(int x, int y)
{
    if(rang[x]>rang[y])
        p[y] = x;
    else
        p[x] = y;
    if(rang[x] == rang[y])
        rang[y]++;
}
void Reuneste(int x, int y)
{
    Uneste(GasesteMultime(x),GasesteMultime(y));
}

void ComponenteConexe( const  vector< pair< int , int > >& v)
{
    for(auto p:v)
        if(GasesteMultime(p.first)!= GasesteMultime(p.second))
           Reuneste(p.first,p.second);
}
int main()
{
    int n,m;
    vector< pair< int , int > > v;
    int x,y;
    in >> n >> m;
    for(int i = 1 ; i <= n ; i++)
        FormeazaMutlime(i);
    for(int i  = 0 ; i < m ; i++)
        in >> x >> y ,v.push_back( make_pair(x,y));
    ComponenteConexe(v);
    unordered_map<int,int> h;
    for(int i = 1 ; i <= n ; i++)
        h[GasesteMultime(i)] = 1;
    out<<h.size();
    return 0;
}