#UF
n,m=map(int,input().split())
n*=2
UFI=[None]+[1]*n
UFH=[None]+[1]*n
def uff(k):
    point=k
    while type(UFH[point])!=int:
        point=int(UFH[point])
    return point
def ufu(k1,k2):
    p1=uff(k1)
    p2=uff(k2)
    if p1==p2:
        return 0
    if UFH[p1]>UFH[p2]:
        p1,p2=p2,p1
    UFI[p2]=UFI[p1]+UFI[p2]
    UFH[p2]=max(UFH[p2],UFH[p1]+1)
    UFH[p1]=str(p2)
for i in range(m):
    a,b=map(int,input().split())
    ufu(a,b)
I=[None]+[0]*n
for i in range(1,n+1):
    I[uff(i)]=1
wans=0
for i in range(1,n+1):
    if I[i] and UFI[i]%2:
        wans+=1
print(wans//2)