v, e = list(map(int,input().split()))

par = [i for i in range(v+1)]



def find(x):

    if par[x] == x:

        return x

    else:

        par[x] = find(par[x])

        return par[x]



def unite(x, y):

    x = find(x)

    y = find(y)

    if x == y:

        return 0

    par[x] = y



for i in range(e):

  a, b = list(map(int, input().split()))

  unite(a, b)

  

cnt = 0

for i in range(v+1):

  if i == par[i]:

    cnt += 1



print((cnt-2))
class UnionFind():

  def __init__(self, n):

    self.n = n

    self.parents = [-1] * n



  def find(self, x):

    if self.parents[x] < 0:

      return x

    else:

      self.parents[x] = self.find(self.parents[x])

      return self.parents[x]



  def union(self, x, y):

    x = self.find(x)

    y = self.find(y)



    if x == y:

        return



    if self.parents[x] > self.parents[y]:

        x, y = y, x



    self.parents[x] += self.parents[y]

    self.parents[y] = x



  def size(self, x):

    return -self.parents[self.find(x)]



  def same(self, x, y):

    return self.find(x) == self.find(y)



  def members(self, x):

    root = self.find(x)

    return [i for i in range(self.n) if self.find(i) == root]



  def roots(self):

    return [i for i, x in enumerate(self.parents) if x < 0]



  def group_count(self):

    return len(self.roots())



  def all_group_members(self):

    return {r: self.members(r) for r in self.roots()}



  def __str__(self):

    return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())

  

v, e = list(map(int, input().split()))

uf = UnionFind(v)

for i in range(e):

  a, b = list(map(int, input().split()))

  uf.union(a-1, b-1)

  

print((uf.group_count()-1))

v, e = list(map(int, input().split()))
par = [i for i in range(v + 1)]


def find(x):
    if par[x] == x:
        return x
    else:
        par[x] = find(par[x])
        return par[x]


def unite(x, y):
    x = find(x)
    y = find(y)
    if x == y:
        return 0
    par[x] = y


for i in range(e):
    a, b = list(map(int, input().split()))
    unite(a, b)
cnt = 0
for i in range(v + 1):
    if i == par[i]:
        cnt += 1
print((cnt - 2))

class UnionFind:
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        if self.parents[x] > self.parents[y]:
            x, y = y, x
        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return "\n".join("{}: {}".format(r, self.members(r)) for r in self.roots())


v, e = list(map(int, input().split()))
uf = UnionFind(v)
for i in range(e):
    a, b = list(map(int, input().split()))
    uf.union(a - 1, b - 1)
print((uf.group_count() - 1))

-v, e = list(map(int, input().split())) -par = [i for i in range(v + 1)] +class UnionFind: +    def __init__(self, n): +        self.n = n +        self.parents = [-1] * n + +    def find(self, x): +        if self.parents[x] < 0: +            return x +        else: +            self.parents[x] = self.find(self.parents[x]) +            return self.parents[x] + +    def union(self, x, y): +        x = self.find(x) +        y = self.find(y) +        if x == y: +            return +        if self.parents[x] > self.parents[y]: +            x, y = y, x +        self.parents[x] += self.parents[y] +        self.parents[y] = x + +    def size(self, x): +        return -self.parents[self.find(x)] + +    def same(self, x, y): +        return self.find(x) == self.find(y) + +    def members(self, x): +        root = self.find(x) +        return [i for i in range(self.n) if self.find(i) == root] + +    def roots(self): +        return [i for i, x in enumerate(self.parents) if x < 0] + +    def group_count(self): +        return len(self.roots()) + +    def all_group_members(self): +        return {r: self.members(r) for r in self.roots()} + +    def __str__(self): +        return "\n".join("{}: {}".format(r, self.members(r)) for r in self.roots()) -def find(x): -    if par[x] == x: -        return x -    else: -        par[x] = find(par[x]) -        return par[x] - - -def unite(x, y): -    x = find(x) -    y = find(y) -    if x == y: -        return 0 -    par[x] = y - - +v, e = list(map(int, input().split())) +uf = UnionFind(v) -    unite(a, b) -cnt = 0 -for i in range(v + 1): -    if i == par[i]: -        cnt += 1 -print((cnt - 2)) +    uf.union(a - 1, b - 1) +print((uf.group_count() - 1))