#include <bits/stdc++.h>

using namespace std;
int noduri,muchii,cnt=0;
bool viz[100005];
queue<int>q;
vector <int>vecin[100005];
void dfs(int nod)
{
    cnt++;
    q.push(nod);
    viz[nod]=1;
    while(!q.empty())
    {
        int nod_curent=q.front();
        q.pop();
        for(auto i:vecin[nod_curent])
            if(!viz[i])
                q.push(i), viz[i]=1;
    }
}
int main()
{
    ifstream cin("dfs.in");
    ofstream cout("dfs.out");
    cin>>noduri>>muchii;
    int x,y;
    for(int i=1; i<=muchii; i++)
    {
        cin>>x>>y;
        vecin[x].push_back(y);
        vecin[y].push_back(x);
    }
    for(int i=1; i<=noduri; i++)
    {
        if(!viz[i])
            dfs(i);
    }
    for(int i=1; i<=noduri; i++)
        cnt+=(1-viz[i]);
    cout<<cnt;
    return 0;
}