class UnionFind:
    def __init__(self, n):
        self.parent = [-1]*n

    def find(self, x):
        if self.parent[x] < 0:
            return x
        self.parent[x] = self.find(self.parent[x])
        return self.parent[x]

    def merge(self, u, v):
        pu, pv = self.find(u), self.find(v)
        if pu==pv: return
        if self.parent[pu] > self.parent[pv]: pu, pv = pv, pu
        self.parent[pu] += self.parent[pv]
        self.parent[pv] = pu

    def leader(self, x):
        return self.find(x)

    def size(self, x):
        return -self.parent[self.find(x)]


def main():
    n, m = map(int, input().split())
    uf = UnionFind(m)
    num = [0]*m
    add = []
    for _ in range(n):
        u, v = map(lambda x: int(x)-1, input().split())
        uf.merge(u, v)
        add.append(u)
    for v in add:
        num[uf.leader(v)] += 1
    s = set()
    for i in range(m):
        s.add(uf.leader(i))
    ans = 0
    for v in s:
        ans += min(num[v], uf.size(v))
    print(ans)


if __name__ == "__main__":
    main()