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, sum):
    visited[n] = True
    check = True
    for v in relation[i]:
        if not visited[v]:
            check = False
            return 1 + dfs(v, sum)
    if check:
        return 1
    

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