#include <stdio.h>

FILE* fin;
FILE* fout;

int Find3(int* roots, int node)
{
	int root = node;
	while (roots[root] != root)
	{
		root = roots[root];
	}

	while (roots[node] != root)
	{
		int tmp = node;
		node = roots[node];
		roots[tmp] = root;
	}

	return root;
}

void Merge3(int* roots, int* layers, int a, int b)
{
	if (layers[a] == layers[b])
	{
		layers[a]++;
		roots[b] = a;
	}
	else
	{
		if (layers[a] > layers[b])
			roots[b] = a;
		else
			roots[a] = b;
	}
}

int main(void)
{
	int n, m;
	int i;
	int finalResult = 0;

	fin = fopen("dfs.in", "r");
	fout = fopen("dfs.out", "w");

	fscanf(fin, "%d %d", &n, &m);

	int* roots = malloc(sizeof(int) * (n + 1));
	int* layers = malloc(sizeof(int) * (n + 1));
	char* isRoot = malloc(sizeof(char) * (n + 1));

	for (i = 1; i <= n; i++)
	{
		roots[i] = i;
	}

	memset(layers, 0, sizeof(int) * (n + 1));
	memset(isRoot, 0, sizeof(char) * (n + 1));

	for (int i = 0; i < m; i++)
	{
		int node1, node2;
		fscanf(fin, "%d %d", &node1, &node2);

		if (Find3(roots, node1) != Find3(roots, node2))
		{
			Merge3(roots, layers, node1, node2);
		}
	}

	for (int i = 1; i <= n; i++)
	{
		isRoot[Find3(roots, i)] = 1;
	}

	for (int i = 1; i <= n; i++)
	{
		if (isRoot[i])
			finalResult++;
	}

	fprintf(fout, "%d", finalResult);

	free(isRoot);
	isRoot = NULL;

	free(layers);
	layers = NULL;

	free(roots);
	roots = NULL;

	fclose(fin);
	fclose(fout);

	return 0;
}