Buggy python submission (verdict: Runtime Error):
from collections import Counter
from operator import itemgetter

N = int(input())
A = list(map(int,input().split())) + [0]
A = list(Counter(A).items())
A  = sorted(A,key=itemgetter(1),reverse = True)
A  = sorted(A,key=itemgetter(0),reverse = True)
#print(A)
ans = 0
for i in range(len(A)):
    if A[i][1] > 1:
        if A[i][1] > 3 :
            ans = max(ans,A[i][0]*2)
        if A[i][1] > 1 and A[i+1][1] > 1:
            ans = max(ans ,A[i][0]*A[i+1][0])
print(ans

Fixed submission:
from collections import Counter
from operator import itemgetter

N = int(input())
A = Counter(map(int,input().split()))
A1 = list(A.items())
A1 = sorted(A1,key=itemgetter(1),reverse = True)
A1 = sorted(A1,key=itemgetter(0),reverse = True)
#print(A1)

#正方形の場合
B =[]
for i in range(len(A1)):
    if A1[i][1] > 3:
        B.append(A1[i][0])
        if len(B) == 1:
            break
C =[]
for i in range(len(A1)):
    if A1[i][1] > 1:
        C.append(A1[i][0])
        if len(C) == 2:
            break

if len(C) == 0:
    print(0)
elif len(B) !=0:
    print(max(B[0]*B[0],C[0]*C[1]))
else:
    print(C[0]*C[1])

Buggy python submission (verdict: Runtime Error):
from collections import Counter
from operator import itemgetter

N = int(input())
A = Counter(map(int,input().split()))
A1 = list(A.items())
A1 = sorted(A1,key=itemgetter(1),reverse = True)
A1 = sorted(A1,key=itemgetter(0),reverse = True)
#print(A1)

#正方形の場合
B =[]
for i in range(len(A1)):
    if A1[i][1] > 3:
        B.append(A1[i][0])
        if len(B) == 1:
            break
C =[]
for i in range(len(A1)):
    if A1[i][1] > 1:
        C.append(A1[i][0])
        if len(C) == 2:
            break

if len(C) == 0:
    print(0)
else:
    print(max(B[0]*2,C[0]*C[1]))


Fixed submission:
from collections import Counter
from operator import itemgetter

N = int(input())
A = Counter(map(int,input().split()))
A1 = list(A.items())
A1 = sorted(A1,key=itemgetter(1),reverse = True)
A1 = sorted(A1,key=itemgetter(0),reverse = True)
#print(A1)

#正方形の場合
B =[]
for i in range(len(A1)):
    if A1[i][1] > 3:
        B.append(A1[i][0])
        if len(B) == 1:
            break
C =[]
for i in range(len(A1)):
    if A1[i][1] > 1:
        C.append(A1[i][0])
        if len(C) == 2:
            break

if len(C) == 0:
    print(0)
elif len(B) !=0:
    print(max(B[0]*B[0],C[0]*C[1]))
else:
    print(C[0]*C[1])

Buggy python submission (verdict: Runtime Error):
from collections import Counter
from operator import itemgetter

N = int(input())
A = Counter(map(int,input().split()))
A1 = list(A.items())
A1 = sorted(A1,key=itemgetter(1),reverse = True)
A1 = sorted(A1,key=itemgetter(0),reverse = True)
#print(A1)

B =[]
for i in range(len(A1)):
    if A1[i][1] > 1:
        B.append(A1[i][0])
        if len(B) == 2:
            break
print(B[1]*B[2] if len(B) !=0 else 0)

Fixed submission:
from collections import Counter
from operator import itemgetter

N = int(input())
A = Counter(map(int,input().split()))
A1 = list(A.items())
A1 = sorted(A1,key=itemgetter(1),reverse = True)
A1 = sorted(A1,key=itemgetter(0),reverse = True)
#print(A1)

#正方形の場合
B =[]
for i in range(len(A1)):
    if A1[i][1] > 3:
        B.append(A1[i][0])
        if len(B) == 1:
            break
C =[]
for i in range(len(A1)):
    if A1[i][1] > 1:
        C.append(A1[i][0])
        if len(C) == 2:
            break

if len(C) == 0:
    print(0)
elif len(B) !=0:
    print(max(B[0]*B[0],C[0]*C[1]))
else:
    print(C[0]*C[1])