//http://judge.openfmi.net:9280/practice/get_problem_description?contest_id=39&problem_id=112
#include <stdio.h>
#include <algorithm>

int main() {
	int n, m;
	scanf("%d%d", &n, &m);
	int i;
	int *first = new int [n]; // the index of the first edge for each node
	int *to = new int [m * 2]; // the node which an edge connects
	int *next = new int [m * 2]; // the index of the next edge from the same node
	
	for (i = 0; i < n; ++i) {
		first[i] = -1;
	}
	
	int counter = 0;
	int x, y;
	for (i = 0; i < m; ++i) {
		scanf("%d%d", &x, &y);
		--x; --y;
		
		to[counter] = y;
		next[counter] = first[x];
		first[x] = counter;
		++counter;
		
		to[counter] = x;
		next[counter] = first[y];
		first[y] = counter;
		++counter;
	}
	
	bool *visited = new bool [n]();
	
	int *curr_front = new int [n];
	int *prev_front = new int [n];
	int curr_size;
	int prev_size;
	int node;
	int edge;
	int to_node;
	
	int result = 0;
	for (i = 0; i < n; ++i) {
		if (!visited[i]) {
			//start traversing the connected component
			++result;
			
			// add the first node as a front
			curr_front[0] = i;
			curr_size = 1;
			visited[i] = true;
			// loop while we have nodes in the front
			while (curr_size) {
				std::swap(curr_size, prev_size);
				std::swap(curr_front, prev_front);
				curr_size = 0;
				
				// for each node in the front:
				// add all its neightbours in the next front
				for (int j = 0; j < prev_size; ++j) {
					node = prev_front[j];
					edge = first[node];
					while (edge != -1) {
						to_node = to[edge];
						if (!visited[to_node]) {
							visited[to_node] = true;
							curr_front[curr_size++] = to_node;
						}
						edge = next[edge];
					}
				}
				// If no more nodes are reachable, the next front will be 0 (curr_size)
				// and the loop ends.
			}
		}
	}
	
	printf("%d\n", result);
}