#include<fstream>
#include<vector>
using namespace std;
ifstream in ("dfs.in" );
ofstream out("dfs.out");
vector<int>ha[200000];
int v[200001],hz[200001];
int n,m,i,st,dr,a,b,j,sol;
int main(){
    in >> n;
    in >> m;
    for( i = 1; i <= m; i ++ ){
        in >> a >> b;
        ha[a].push_back(b);
        ha[b].push_back(a);
    }

    for( j = 1; j <= n; j ++ ){
        if( hz[j] == 0 ){
            sol ++;
            v[1] = j;
            hz[j] = 1;
            for( st = 1,dr = 1; st <= dr; st ++ ){
                for( i = 0; i < ha[v[st]].size(); i ++ ){
                    if( hz[ ha[v[st]][i] ] == 0 ){
                        dr ++;
                        v[dr] = ha[v[st]][i];
                        hz[ha[v[st]][i] ] = 1;
                    }
                }
            }
        }
    }
    out<<sol;

    return 0;
}