import sys
from atcoder.dsu import DSU


def main():
    data = sys.stdin.buffer.read().split()
    n = int(data[0])
    m = int(data[1])
    d = DSU(n)
    for i in range(m):
        d.merge(int(data[2 + 2 * i]), int(data[3 + 2 * i]))
    print(sum(1 for i in range(n) if d.leader(i) == i))


main()