'''
YC2403
"Eight" Bridges of Königsberg
有向グラフに辺を追加して、各辺を１回ずつ通るようにする
最小追加変数は幾つか?
必要な条件
・連結であること
・出次数と入次数がすべて等しいか、差が+1の頂点と-1の頂点が1個ずつある


'''
def root(x):
    if P[x] < 0: return x
    P[x] = root(P[x])  # 経路圧縮
    return P[x]

def unite(x,y):
    x = root(x)
    y = root(y)
    if x == y: return
    if x > y: x,y = y,x
    P[x] += P[y]
    P[y] = x

def same(x,y):
    return root(x) == root(y)

def size(x):
    x = root(x)
    return -P[x]

def group_count():
    S = set()
    for i in range(N+1):
        if size(i) > 1:
            S.add(root(i))
        if size(i) == 1 and G[i] == True:
            S.add(i)

    return len(S)

N,M = map(int,input().split())
P = [-1] * (N + 1)

UV = [list(map(int,input().split())) for _ in range(M)]
F = [[0,0] for _ in range(N+1)]
G = [False] * (N+1)
for u,v in UV:
    F[u][0] += 1
    F[v][1] += 1
    G[u] = True
    G[v] = True
    unite(u,v)
tmp = group_count()
tmp2 = 0
for i in range(N+1):
    tmp2 += abs(F[i][0] - F[i][1])
tmp2 //= 2
if tmp2 > 0:
    tmp2 -= 1
print(tmp2 + tmp - 1)