# ★　ac-library 動作確認

from collections import deque

def bfs(G,check,now):

    dq = deque([now])

    while dq:
        now = dq.popleft()
       
        for to in G[now]:
            if check[to]:
                continue
            check[to] = True
            dq.append(to)

    return check


def main():

    N,M = map(int, input().split())
    G = [[] for _ in range(N)]
    for _ in range(M):
        u,v = map(int, input().split())
        G[u].append(v)
        G[v].append(u)

    ans = 0

    check = [False]*N

    for now in range(N):
        if check[now]:
            continue
        check[now] = True
        ans += 1
        check = bfs(G,check,now)

    print(ans)

if __name__ == "__main__":
    main()