#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

ifstream fin("dfs.in");
ofstream fout("dfs.out");

vector <int> mat[100002];
int viz[100002], n, m, x, y, contor;

void dfs(int v)
{
    viz[v]=1;
    for(int i=0;i<mat[v].size();i++)
    {
        viz[mat[v][i]]=1;
    }
}

int main()
{
    fin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        fin>>x>>y;
        mat[x].push_back(y);
        mat[y].push_back(x);
    }
    for(int i=1;i<=n;i++)
    {
        if(viz[i]==0)
        {
            dfs(i);
            contor++;
        }
    }
    fout<<contor;
    return 0;
}