#include<bits/stdc++.h>
using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
const int nmax=100001;
int n,m;
int x,y;
vector<vector<int>> graph;
bitset<nmax>used;
void dfs(int node)
{
    used[node]=1;
    for(int next:graph[node])
    {
        if(used[next]!=0)
            dfs(next);
    }
}

int main()
{
fin>>n>>m;
int comp_conexe=0;
graph.assign(n+1,vector<int>());
fin>>x>>y;
for(int i=1; i<=m;i++)
    {
    fin>>x>>y;
    graph[x].push_back(y);
    graph[y].push_back(x);
   }
  for(int i=1; i<=n;i++)
  {
   if(used[i]!=0)
   {
        comp_conexe++;
        dfs(i);
   }
  }

}
fout<<comp_conexe;
return 0;
}