#include <fstream>
#include <cstdio>
#include <vector>
#define VAL 100005

using namespace std;

int N, M, i, x;
int a, b, ans;
bool ok[VAL];
vector<int> v[VAL];
vector<int>:: iterator it;

void dfs(int x)
{
    for (it=v[x].begin(); it!=v[x].end(); it++)
    {
        if (ok[*it]==false)
        {
            x++;
            ok[*it]=true;
            dfs(*it);
        }
    }
}

int main()
{
    freopen("dfs.in", "r", stdin);
    freopen("dfs.out", "w", stdout);
    scanf("%d %d", &N, &M);
    for (i=1; i<=M; i++)
    {
        scanf("%d %d", &a, &b);
        v[a].push_back(b);
        v[b].push_back(a);
    }
    for (i=1; i<=N; i++)
    {
        if (ok[i]==false)
        {
            ok[i]=true;
            ans++;
            dfs(i);
        }
    }
    printf("%d\n", ans);
    return 0;
}