import sys; input = lambda: sys.stdin.readline().rstrip()
def find(x):
if par[x] == x:
return x
par[x] = find(par[x])
return par[x]
def union(a, b):
a = find(a)
b = find(b)
if a == b:
return
if rnk[a] > rnk[b]:
par[b] = a
elif rnk[a] < rnk[b]:
par[a] = b
else:
par[b] = a
rnk[a] += 1
n,m = map(int, input().split())
par = [i for i in range(n+1)]
rnk = [1 for _ in range(n+1)]
for i in range(m):
a, b = map(int, input().split())
union(a, b)
ans = set()
for i in range(1, n+1):
ans.add(find(i))
print(len(ans))