Buggy python submission (verdict: Runtime Error):
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.add(x+1)
    for u in d[x]:
        if vis[u]==0:
            dfs(u)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=set()
        dfs(i)
        l=0
        z=0
        for j in a:
            if p[j-1] in a:
                z+=1
            if p[j-1]==j:
                l+=1
        ans=max(ans,c+z-l)
print(ans)
        
                
                
    
    
    
    

Fixed submission:
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
from collections import deque
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.add(x+1)
    
    di = deque()
    di.append(x)
    while di:
        now = di.popleft()
        for j in d[now]:
            if not vis[j]:
                vis[j] = 1
                a.add(j+1)
                di.append(j)
    
    
    for u in d[x]:
        if vis[u]==0:
            dfs(u)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=set()
        dfs(i)
        l=0
        z=0
        for j in a:
            if p[j-1] in a:
                z+=1
            if p[j-1]==j:
                l+=1
        ans=max(ans,c+z-l)
print(ans)

Buggy python submission (verdict: Runtime Error):
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.append(x+1)
    for u in d[x]:
        if vis[u]==0:
            dfs(u)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=[]
        dfs(i)
        l=0
        z=0
        for j in a:
            if p[j-1] in a:
                z+=1
            if p[j-1]==j:
                l+=1
        ans=max(ans,c+z-l)
print(ans)
        
                
                
    
    
    
    

Fixed submission:
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
from collections import deque
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.add(x+1)
    
    di = deque()
    di.append(x)
    while di:
        now = di.popleft()
        for j in d[now]:
            if not vis[j]:
                vis[j] = 1
                a.add(j+1)
                di.append(j)
    
    
    for u in d[x]:
        if vis[u]==0:
            dfs(u)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=set()
        dfs(i)
        l=0
        z=0
        for j in a:
            if p[j-1] in a:
                z+=1
            if p[j-1]==j:
                l+=1
        ans=max(ans,c+z-l)
print(ans)

Buggy python submission (verdict: Runtime Error):
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.append(x+1)
    for i in d[x]:
        if vis[i]==0:
            dfs(i)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=[]
        dfs(i)
        l=0
        z=0
        for i in a:
            if p[i-1] in a:
                z+=1
            if p[i-1]==i:
                l+=1
        ans=max(ans,c+z-l)
print(ans)
        
                
                
    
    
    
    

Fixed submission:
n,m=list(map(int,input().split()))
p=list(map(int,input().split()))
from collections import defaultdict
from collections import deque
c=0
for i in range(n):
    if p[i]==i+1:
        c+=1
vis=[0]*n
def dfs(x):
    vis[x]=1
    a.add(x+1)
    
    di = deque()
    di.append(x)
    while di:
        now = di.popleft()
        for j in d[now]:
            if not vis[j]:
                vis[j] = 1
                a.add(j+1)
                di.append(j)
    
    
    for u in d[x]:
        if vis[u]==0:
            dfs(u)
d=defaultdict(list)
for i in range(m):
    a,b=list(map(int,input().split()))
    d[a-1].append(b-1)
    d[b-1].append(a-1)
ans=0
for i in range(n):
    if vis[i]==0:
        a=set()
        dfs(i)
        l=0
        z=0
        for j in a:
            if p[j-1] in a:
                z+=1
            if p[j-1]==j:
                l+=1
        ans=max(ans,c+z-l)
print(ans)