class UnionFind:
    def __init__(self, n):
        self.par = [i for i in range(n + 1)]
        self.rank = [0] * (n + 1)

    # search
    def find(self, x):
        if self.par[x] == x:
            return x
        else:
            self.par[x] = self.find(self.par[x])
            return self.par[x]

    # unite
    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if self.rank[x] < self.rank[y]:
            self.par[x] = y
        else:
            self.par[y] = x
            if self.rank[x] == self.rank[y]:
                self.rank[x] += 1

    # check
    def same_check(self, x, y):
        return self.find(x) == self.find(y)


n, m = map(int, input().split())
ab_list = [tuple(map(int, input().split())) for _ in range(m)]

uf = UnionFind(n)
for a, b in ab_list:
	uf.union(a, b)

p_count = [0] * (n + 1)
for i in range(n):
	p = uf.find(i + 1)
	p_count[p] += 1

res = n
for i in range(n):
	res -= p_count[i + 1] // 2

print(res)