#include <iostream>
#include <fstream>
#include <vector>

using namespace std;
int n,m,x,y,i,j,k,viz[100001],nc,ok;
ifstream f("dfs.in");
ofstream g("dfs.out");

vector <int> G[100001];

void dfs(int k)
{
    int i;
    viz[k]=nc;
    for(i=0;i<G[k].size();i++)
    {    y=G[k][i];
        if(viz[y]==0) dfs(y);
    }
}

int main()
{

   f>>n>>m;
   for(i=1;i<=m;i++)
   {
       f>>x>>y;
        G[x].push_back(y);
        G[y].push_back(x);
   }
   nc=1;
   x=1;
   do
   {
       ok=1;
       dfs(x);
       for(j=1;j<=n;j++)
        if(viz[j]==0)
       {
           ok=0;
           nc++;
           x=j;
           break;
       }

   } while (ok==0);
   g<<nc<<endl;

    return 0;
}