#include <fstream>
#include <vector>
#include <stack>
#define MAX 100004
using namespace std;
vector<int> v[MAX];
vector<int> q;
int n, m;
int vis[MAX];
void read();
void dfs();
bool checkStack(int x);
int main()
{
read();
dfs();
return 0;
}
void read(){
ifstream fin ("dfs.in");
fin >> n >> m;
int x, y;
for (int i = 1; i <= m; ++i){
fin >> x >> y;
v[x].push_back(y);
v[y].push_back(x);
}
fin.close();
}
void dfs(){
int k(0);
for (int i = 1; i <= n; ++i){
if (vis[i])
continue;
++k;
q.push_back(i);
while(!q.empty()){
int u = q.back();
q.pop_back();
if (!vis[u] && checkStack(u))
{
vis[u] = 1;
for (unsigned int i = 0; i < v[u].size(); ++i)
if (!vis[v[u][i]])
q.push_back(v[u][i]);
}
}
}
ofstream fout ("dfs.out");
fout << k;
fout.close();
}
bool checkStack(int x){
for (unsigned int i = 0; i < q.size(); ++i)
if (q[i] == x)
return 0;
return 1;
}