Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = [0]*N
Origin = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK[i] = 1
        Origin.append(i)
ans = 0
for i in range(N):
    c = 0
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = Origin.copy()
        Enable.append(i)
        T = OK.copy()
        T[P[i]] = 1
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    T[P[j]] = 1
                    S.append(j)
        Enable = list(set(Enable))
        for j in Enable:
            if T[j] == 1:
                c += 1
        ans = max(ans, c)

print(ans)

Fixed submission:
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
        T_1 = list(set(OK + Enable))
        T_2 = list(set(OK + Origin))
        ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = [0]*N
Origin = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK[i] = 1
        Origin.append(i)
ans = 0
for i in range(N):
    c = 0
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = Origin.copy()
        Enable.append(i)
        T = OK.copy()
        T[P[i]] = 1
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    T[P[j]] = 1
                    S.append(j)
    Enable = list(set(Enable))
    for j in Enable:
        if T[j] == 1:
            c += 1
    ans = max(ans, c)

print(ans)

Fixed submission:
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
        T_1 = list(set(OK + Enable))
        T_2 = list(set(OK + Origin))
        ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
    T_1 = set(OK + Enable)
    T_2 = set(OK + Origin)
    T_3 = set(OK + Enable + Origin)
    ans = max(ans, len(T_1) + len(T_2) - len(T_3))

print(ans)


Fixed submission:
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
        T_1 = list(set(OK + Enable))
        T_2 = list(set(OK + Origin))
        ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
import copy
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = deque(OK.copy())
        Origin = deque(OK.copy())
        T_3 = deque(OK.copy())
        Enable.append(i)
        Origin.append(P[i])
        T_3.append(i)
        T_3.append(P[i])
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    T_3.append(j)
                    T_3.append(P[j])
                    S.append(j)
    T_1 = list(set(Enable))
    T_2 = list(set(Origin))
    ans = max(ans, len(T_1) + len(T_2) - len(set(T_3)))

print(ans)

Fixed submission:
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
        T_1 = list(set(OK + Enable))
        T_2 = list(set(OK + Origin))
        ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
    T_1 = list(set(OK + Enable))
    T_2 = list(set(OK + Origin))
    ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)

Fixed submission:
from collections import deque
N, M = map(int, input().split())
P = list(map(int, input().split()))
K = [[] for _ in range(N)]
for i in range(M):
    x, y = map(int, input().split())
    x, y = x-1, y-1
    K[x].append(y)
    K[y].append(x)
used = [0]*N
OK = []
for i in range(N):
    P[i] -= 1
    if i == P[i]:
        OK.append(i)
ans = 0
for i in range(N):
    if used[i] == 0:
        used[i] = 1
        S = deque([i])
        Enable = [i]
        Origin = [P[i]]
        while S:
            t = S.popleft()
            for j in K[t]:
                if used[j] == 0:
                    used[j] = 1
                    Enable.append(j)
                    Origin.append(P[j])
                    S.append(j)
        T_1 = list(set(OK + Enable))
        T_2 = list(set(OK + Origin))
        ans = max(ans, len(T_1) + len(T_2) - len(set(T_1 + T_2)))

print(ans)