## https://yukicoder.me/problems/no/2418


class UnionFind:
    """
    UnionFindの基本的な処理を実装したクラス
    """

    def __init__(self, size):
        self.root = [i for i in range(size)]
        self.size = [1] * size

    def get_root(self, v):
        if v == self.root[v]:
            return v
        else:
            old_root = self.root[v]
            new_root = self.get_root(old_root)
            self.root[v] = new_root
            return new_root

    def merge(self, u, v):
        root_u = self.get_root(u)
        root_v = self.get_root(v)
        if root_u == root_v:
            return False

        if self.size[root_u] >= self.size[root_v]:
            self.size[root_u] += self.size[root_v]
            self.root[root_v] = root_u
            self.root[v] = root_u
        else:
            self.size[root_v] += self.size[root_u]
            self.root[root_u] = root_v
            self.root[u] = root_v
        return True
    

def main():
    N, M = map(int, input().split())
    ab = []
    for _ in range(M):
        a, b = map(int, input().split())
        ab.append((a - 1, b - 1))
    uf = UnionFind(2 * N)
    for a, b in ab:
        uf.merge(a, b)

    a_map = {}
    for i in range(2 * N):
        r_i = uf.get_root(i)
        if r_i not in a_map:
            a_map[r_i] = 0
        a_map[r_i] += 1

    answer= 0
    for value in a_map.values():
        answer += value % 2
    print(answer // 2)

   
   




if __name__ == "__main__":
    main()