#include <bits/stdc++.h>

using namespace std;

//ifstream f("file.in");
ifstream f("dfs.in");
ofstream g("dfs.out");

int n, m, X;

vector<int> G[10000];

void read() {

    f>>n>>m;//>>X;

    for(int i=0; i<m; i++) {
        int x, y;
        f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
        sort(G[x].begin(), G[x].end());
        sort(G[y].begin(), G[y].end());
    }
}

bool verif[10000];

void dfs(int nodStart) {

    //cout<<nodStart<<" ";
    verif[nodStart] = true;
    for(int i=0; i<G[nodStart].size(); i++) 
        if(!verif[G[nodStart][i]])
            dfs(G[nodStart][i]);
   

}

int main() {
    int nr = 0;
    bool ok = true;
    read();
   while(1) {
        for(int i=1; i<=n; i++) {
            if(!verif[i]) {
                nr++;
                dfs(i);
                ok = false;
            }
        }
        if(ok == true)
            break;
        else 
            ok = true;
   }
    //dfs(X);
    g<<nr;

    return 0;
}