#include <bits/stdc++.h>
#define pb push_back
#define NMAX 100005
using namespace std;

struct nod{
    vector<int> adj;
};
vector<nod> v;
int n,m,x,y;
bitset<NMAX> viz;
void dfs(int root)
{
    stack<int> s;
    int nod,w;
    bool ok=1;
    s.push(root);
    viz[root]=1;
    while (!s.empty())
    {
        nod = s.top();
        ok=0;
        for (int i=0;i<v[nod].adj.size();i++)
        {
            w=v[nod].adj[i];
            if (!viz[w])
            {
                ok=1;
                s.push(w);
                viz[w]=1;
                break;
            }
        }
        if (!ok) s.pop();
    }
}
void comp()
{
    int k=0;
    for (int i=1;i<=n;i++)
    {
        if (!viz[i])
        {
            dfs(i);
            k++;
        }
    }
    printf("%d", k);
}
int main()
{
    freopen("dfs.in", "r", stdin);
    freopen("dfs.out", "w", stdout);

    scanf("%d %d", &n, &m);
    v.resize(n+2);
    for (int i=0;i<m;i++)
    {
        scanf("%d %d", &x, &y);
        v[x].adj.pb(y);
        v[y].adj.pb(x);
    }
    comp();
    fclose(stdin);
    fclose(stdout);
    return 0;
}