def dfs(pos):
    if pos in s or vis[pos]: return
    s.add(pos)
    vis[pos] = True
    for i in g[pos]:
        dfs(i)

n,m = map(int,input().split())
g = [[] for _ in range(2*n)]

for i in range(m):
    a,b = map(int,input().split())
    a -= 1
    b -= 1
    g[a].append(b)
    g[b].append(a)

cnt = 0
vis = [False]*(2*n)
for i in range(2*n):
    s = set()
    if g[i] == []:
        cnt += 1
    elif not vis[i]:
        dfs(i)
        cnt += len(s) % 2

print(cnt // 2)