#include <fstream>
using namespace std; 
ifstream cin("dfs.in");
ofstream cout("dfs.out");
#define Nmax 100013
 
class cell {
  public : 
 	int node;
 	cell *prev;
 	cell (int a, cell *l) { node=a; prev=l; l=prev;};
 };
 	  
 class UndirectedGraph {
 	 private : 
 	          cell *adj[Nmax];
 	          bool used[Nmax];
 	          
 	          bool dfs(int node){
 	          	used[node]=1;
 	          	for (cell *it = adj[node];it;it=it->prev)
 	          	   if (!used[it->node])
 	          	     dfs(it->node);
          	     return 1;
 	          	 }
 	 public : 
 		      void addEdge(int a,int b){
 		      	 cell *aux = new cell(b,adj[a]);
 		      	       aux = new cell(a,adj[b]);
 		      }
 		      
 		      int conexCnt(int nodes){
 		      	int sol=0;
 		      	  for (int i=1;i<=nodes;++i) 
 		      	     if (!used[i]) 
      	                sol+=dfs(i);
               return sol;
 		      }
 } Graph;
 
int n,m,a,b;
int main(void) {
 cin>>n>>m;
 while(m--) {
 	cin>>a>>b;
 	Graph.addEdge(a,b);
    }
 cout<<Graph.conexCnt(n);
 return 0;
}