#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>
#define Nmax 100009
#define pb push_back
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");

int N,M,sol,x,y,k;
vector < int > G[Nmax];
int comp[Nmax],st[Nmax];

inline void GetCC(int S)
{
    for( st[++k]=S; k;)
    {
        int node = st[k--];
        comp[node]=sol;
        while(G[node].size()>0)
        {
            int fiu=G[node].back();
            if(!comp[fiu])comp[fiu]=sol , st[++k]=fiu;
            G[node].pop_back();
            G[fiu].erase(find(G[fiu].begin(),G[fiu].end(),node));
        }
    }
}

int main()
{
    f>>N>>M;
    for (int i=1; i<=M; ++i)
        f>>x>>y , G[x].pb(y) , G[y].pb(x);
    for (int i=1; i<=N; ++i)
      if (!comp[i])
            ++sol , GetCC(i);
    g<<sol<<'\n';
    f.close(); g.close();
    return 0;
}