#include <iostream>
#include <fstream>
#include <vector>
#include <stack>
#define N 100001

using namespace std;

vector<int> g[N];
int n;

void citire()
{
    int m;
    ifstream fin("dfs.in");
    fin >> n >> m;
    for(int i=1; i<=m; i++)
    {
        int x,y;
        fin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    fin.close();
}

bool visited[N];

void dfs(int src)
{
    stack<int> s;
    visited[src] = true;
    s.push(src);
    while(!s.empty())
    {
        int x = s.top();
        s.pop();
        vector<int>::iterator i;
        for(i = g[x].begin(); i!=g[x].end(); ++i)
            if(!visited[*i])
        {
            visited[*i] = true;
            s.push(*i);
        }
    }
}

void stuff()
{
    int count = 0;
    int ok;
    do
    {
        ok = 0;
        for(int i=1; i<=n; i++)
            if(!visited[i])
            {
                ok = 1;
                count++;
                dfs(i);
            }
    }while(ok);
    ofstream fout("dfs.out");
    fout << count;
    fout.close();
}

int main()
{
    citire();
    stuff();
    return 0;
}