[구름] 그룹 지정.py

# -*- coding: utf-8 -*-
# UTF-8 encoding when using korean
import sys
def find_parent(x, parent):
	if x not in parent or x == parent[x]:
		return x
	p = find_parent(parent[x], parent)
	parent[x] = p
	return p

def union_find(x, y, parent):
	x = find_parent(x, parent)
	y = find_parent(y, parent)
	if x != y:
		parent[y] = x

n, m = map(int, sys.stdin.readline().split())
parent = dict()
for _ in range(m):
	a, b = map(int, sys.stdin.readline().split())
	# a, b 오름차순으로 변경
	if b < a:
		a, b = b, a
	# a 학생 기준으로 그룹화
	union_find(a, b, parent)

print(len(set(find_parent(i, parent) for i in range(1, n+1))))