#include <fstream>
#include <vector>
using namespace std;ifstream f("dfs.in");ofstream g("dfs.out");int n,m,s,k;bool viz[100001];vector<int>a[100001];void dfs(int src){viz[src]=true;for(int i=0;i<a[src].size();++i){if(!viz[a[src][i]])dfs(a[src][i]);}}int main(){f>>n>>m;viz[s]=true;for(int i=1;i<=m;++i){int x,y;f>>x>>y;a[x].push_back(y);a[y].push_back(x);}for(int i=1;i<=n;++i){if(!viz[i]){dfs(i);k++;}}g<<k;return 0;}