f=open("dfs.in",'r')
w=open("dfs.out",'w')
line=f.readline().split()
n,m=int(line[0]), int(line[1])
a=[[] for _ in range(n+1)]
line=f.readline().split()
while line:
    line=[int(line[i]) for i in range(len(line))]
    a[line[0]].append(line[1])
    a[line[1]].append(line[0])
    line=f.readline().split()
viz=[0 for _ in range(n+1)]
k=0

def dfs(a, i):
    viz[i]=1
    for j in a[i]:
        if viz[j]==0:
            viz[j]=1
            dfs(a,j)

for i in range(1,n+1):
    if viz[i]==0:
        dfs(a,i)
        viz[i]=1
        k+=1

w.write(str(k))
w.close()
f.close()