Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline
from heapq import heappush,heappop
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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  groupnumber = uf.group_count()
  ans = 0
  for key,value in uf.all_group_members().items():
    tmp = []
    for val in value:
      heappush(tmp,p[val]-1)
      heappush(tmp,val)
    now = -1
    while tmp:
      next = heappop(tmp)
      if next == now:
        ans += 1
      now = next
  print(ans)

    
solve()

Fixed submission:
import sys
input = sys.stdin.readline
from heapq import heappush,heappop
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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  ans = 0
  for i in range(n):
    if uf.same(i,p[i]-1):
      ans += 1
  print(ans)
    
solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  groupnumber = uf.group_count()
  ans = 0
  for key,value in uf.all_group_members().items():
    tmp = []
    for val in value:
      tmp.append(p[val]-1)
      tmp.append(val)
    tmp = sorted(tmp)
    for i in range(len(tmp)-1):
      if tmp[i] == tmp[i+1]:
        ans += 1
  print(ans)

    
solve()

Fixed submission:
import sys
input = sys.stdin.readline
from heapq import heappush,heappop
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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  ans = 0
  for i in range(n):
    if uf.same(i,p[i]-1):
      ans += 1
  print(ans)
    
solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())
  xy = []

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    if x > y:
      x,y = y,x
    xy.append((x,y))
    uf.union(x-1,y-1)
  groupnumber = uf.group_count()
  ans = 0
  for key,value in uf.all_group_members().items():
    length = len(value)
    for i in range(length):
      val = p[value[i]]
      value.append(val-1)
    length = len(value)
    tmp = len(set(value))
    ans += length-tmp
  print(ans)

    
solve()

Fixed submission:
import sys
input = sys.stdin.readline
from heapq import heappush,heappop
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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  ans = 0
  for i in range(n):
    if uf.same(i,p[i]-1):
      ans += 1
  print(ans)
    
solve()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
input = sys.stdin.readline

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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())
  xy = []

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    if x > y:
      x,y = y,x
    xy.append((x,y))
    uf.union(x-1,y-1)
  groupnumber = uf.group_count()
  ans = 0
  for key,value in uf.all_group_members().items():
    length = len(value)
    for i in range(length):
      val = p[value[i]]
      value.append(val-1)
    length = len(value)
    tmp = len(set(value))
    ans += length-tmp
  print(ans)

    
solve()

Fixed submission:
import sys
input = sys.stdin.readline
from heapq import heappush,heappop
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 solve():
  n,m = (int(i) for i in input().split())
  p = list(int(i) for i in input().split())

  uf = UnionFind(n)
  for i in range(m):
    x,y = (int(i) for i in input().split())
    uf.union(x-1,y-1)
  ans = 0
  for i in range(n):
    if uf.same(i,p[i]-1):
      ans += 1
  print(ans)
    
solve()