#include<fstream>
#include<vector>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
int n,m,x,y,i,nr=1,nin;
bool este[100001],ok;
vector<int> v[100001];
void dfs(int k)
{
    int j;
    for(j=0;j<v[k].size();++j)
      if(!este[v[k][j]])
        {
            este[v[k][j]]=1;
            dfs(j);
        }
}
int main()
{
    f>>n>>m;
    nin=1;
    for(i=1;i<=m;++i)
      {
          f>>x>>y;
          v[x].push_back(y);v[y].push_back(x);
      }
    while(!ok)
      {
          dfs(nin);
          for(i=nin;i<=n;i++)
            {if(!este[i])
               {
                  nr++;
                  dfs(i);
                  break;
               }
             ok=1;
            }
         nin++;
      }
   g<<nr;
   f.close();g.close();
   return 0;
}