N, M = map(int, input().split())

G = [ [] for _ in range(N+1)]

for _ in range(M):
    u, v = map(int, input().split())
    G[u].append(v)

odd = 0
even = 0

for val in G:
    if len(val) % 2 != 0:
        odd += 1
    else:
        even += 1
if odd > 2:
    print(odd - 2)
elif odd == 1:
    print(1)
else:
    print(0)