#include <cstdio>
#include <algorithm>
#define NMAX 100010
using namespace std;


struct nod
{
	int val;
	nod *next;
};

nod *v[NMAX];
int M, N, i, k, x, y;
bool viz[NMAX];

void Add(nod *&h, int w)
{
	nod *p;
	p =	new nod;	
	p -> val = w;
	p -> next = h;
	h = p;
}
void read(void)
{
	freopen("dfs.in", "r", stdin);
	scanf("%d%d", &N, &M);
	
	for(i = 1; i <= M; ++i)
	{
		scanf("%d%d", &x, &y);
		Add(v[x], y);
		Add(v[y], x);
	}
	
	fclose(stdin);
		
}
void DF(int poz)
{
	viz[poz] = 1;
	for(nod *p = v[poz]; p; p = p -> next)
		if( viz[ p->val ] == 0)
			DF(p -> val);
}
void solve(void)
{
	for(i = 1; i <= N; ++i)
		if(!viz[i])
			DF(i), ++k;
		
}
void print(void)
{
	freopen("dfs.out", "w", stdout);
	printf("%d\n", k);
	
	fclose(stdout);
}
int main(void)
{
	read();
	solve();
	print();
	
	return 0;
}