#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
ifstream in("dfs.in");
ofstream out("dfs.out");


vector <int> v[500005];
bool b[500005];

int n, m, x, y, cont;

void dfs(int nod){
    b[nod]=1;
    for(auto i:v[nod]){
        if(!b[i]){
            dfs(i);
        }

    }
}




int main()
{
    in>>n>>m;
    for(int i=1;i<=m;i++){
        in>>x>>y;
        v[y].push_back(x);
        v[x].push_back(y);
    }
    for(int i=1;i<=n;i++){
        if(b[i]!=1){
            cont++;
            dfs(i);
        }
    }
    out<<cont;
}