#include <fstream>
#include <vector>
using namespace std;
const int nmax=100001;
int k=0;
ofstream fout("dfs.out");
void citire(vector<int> G[],int &N,int &M)
{
 ifstream fin("dfs.in");
 fin>>N>>M;
 int x,y;
  for(int i=1;i<=M;i++)
  {
    fin>>x>>y;
    G[x].push_back(y);
    G[y].push_back(x);
  }
 fin.close();
}
void DFS(vector<int>G[],int nod,bool V[])
{
  V[nod]=true;
  //fout<<nod<<" ";
  k++;
  for(int i=0;i<G[nod].size();i++)
      if(V[G[nod][i]]==false) DFS(G,G[nod][i],V);
}
int main()
{
int N,M;
bool V[nmax];
vector <int> G[nmax];
citire(G,N,M);
for(int i=1;i<=N;++i)
V[i]=false;
DFS(G,1,V);

fout<<k;


return 0;
}