#include <iostream>
#include <algorithm>
#include <stack>
#include <cstring>
#include <vector>
#include <fstream>
#include <queue>
#include <bitset>

#define pb push_back
#define mp make_pair
#define dim 100009

using namespace std;
ofstream out("dfs.out");

int n,m;
bitset<dim> uz;
int sol;

vector < int > G[dim];
typedef vector < int >::iterator IT;


void read();
void dfs(int source);
void iterativeDfs(int source);

int main()
{
    read();
    for(int i = 1 ; i<=n; ++i)
        if(!uz[i])
    {
        ++sol;
        iterativeDfs(i);
    }

    out << sol << '\n';

    return 0;
}

void read()
{
    ifstream in("dfs.in");

    in >> n >> m;
    for(int x,y; m; --m)
    {
        in >> x >> y;
        G[x].pb(y);
        G[y].pb(x);
    }
}

void dfs(int source)
{
    uz[source] = 1;
    for(IT i = G[source].begin(); i!=G[source].end(); ++i)
        if(!uz[*i])
    {
        dfs(*i);
    }

}

void iterativeDfs(int source)
{
    stack<int> St;
    St.push(source);
    uz[source] = 1;

    while(!St.empty())
    {
        int vf = St.top();
        int ans = -1;

        for(IT i = G[vf].begin(); i!=G[vf].end(); ++i)
        {
            if(!uz[*i])
                {
                    ans = *i;
                    break;
                    //am gasit un vecin ok
                }
        }

        if(ans != -1)
        {
            St.push(ans);
            uz[ans] = 1;
        }
        else
        {
            St.pop();
        }
    }
}