N,M = map(int,input().split())

parent = list(range(N+1))
import sys
sys.setrecursionlimit(10 ** 8)
def find(i):
    if parent[i] == i:return i
    parent[i] = find(parent[i])
    return parent[i]
def unite(i,j):
    I = find(i)
    J = find(j)
    if I == J:return False
    parent[I] = J
    parent[i] = J
    return True
for _ in range(M):
    a,b = map(int,input().split())
    unite(a,b)
ans = 0
for i in range(1,N+1):
    if parent[i] == i:
        ans += 1
print(ans)