import sys

sys.setrecursionlimit(1000000)

n, m = map(int, input().split())
relation = [[] for _ in range(2*n)]
visited = [False]*(2*n)
unknown = 0

for _ in range(m):
    a, b = map(int, input().split())
    a -= 1; b -= 1
    relation[a].append(b)
    relation[b].append(a)
    
def dfs(n: int):
    global len_of_group_member
    len_of_group_member += 1
    visited[n] = True
    for v in relation[n]:
        if not visited[v]:
            dfs(v)

for i in range(2*n):
    if not visited[i]:
        len_of_group_member = 0
        dfs(i)
        unknown += len_of_group_member % 2
print(unknown // 2)