Buggy python submission (verdict: Runtime Error):
def solve(): # 071C - Make a Rectangle
    n = int(input())
    sides = list(map(int, input().split(" ")))
    check_dual = {}
    possible_sides = []

    for i in sides:
        if i in check_dual:
            check_dual[i] += 1
        else:
            check_dual[i] = 1

    tmp_square = 0
    for k, v in check_dual.items():
        if v >= 4 and k > tmp_square:
            tmp_square = k
        elif v == 2 or v == 3:
            possible_sides.append(k)
        else:
            pass

    possible_sides.sort(reverse=True)
    if tmp_square == 0 and len(possible_sides) < 2:
        print(0)
    else:
        print(max(possible_sides[0] * possible_sides[1],
                  tmp_square ** 2))


solve()

Fixed submission:
def solve(): # 071C - Make a Rectangle
    n = int(input())
    sides = list(map(int, input().split(" ")))
    check_dual = {}
    possible_sides = []

    for i in sides:
        if i in check_dual:
            check_dual[i] += 1
        else:
            check_dual[i] = 1

    tmp_square = 0
    for k, v in check_dual.items():
        if v >= 4 and k > tmp_square:
            tmp_square = k
            possible_sides.append(k)
        elif v == 2 or v == 3:
            possible_sides.append(k)
        else:
            pass

    possible_sides.sort(reverse=True)
    if tmp_square == 0 and len(possible_sides) < 2:
        print(0)
    elif tmp_square != 0 and len(possible_sides) == 0:
        print(tmp_square ** 2)
    elif tmp_square != 0 and len(possible_sides) == 1:
        print(max(tmp_square ** 2, tmp_square * possible_sides[0]))
    else:
        print(max(tmp_square ** 2, possible_sides[0] * possible_sides[1]))

solve()

Buggy python submission (verdict: Runtime Error):
def solve(): # 071C - Make a Rectangle
    n = int(input())
    sides = list(map(int, input().split(" ")))
    check_dual = {}
    possible_sides = []

    for i in sides:
        if i in check_dual:
            check_dual[i] += 1
        else:
            check_dual[i] = 1

    tmp_square = 0
    for k, v in check_dual.items():
        if v >= 4 and k > tmp_square:
            tmp_square = k
        elif v == 2 or v == 3:
            possible_sides.append(k)
        else:
            pass

    possible_sides.sort(reverse=True)
    if tmp_square == 0 and len(possible_sides) < 2:
        print(0)
    else:
        print(max(possible_sides[0] * possible_sides[1],
                  tmp_square ** 2))


solve()

Fixed submission:
def solve(): # 071C - Make a Rectangle
    n = int(input())
    sides = list(map(int, input().split(" ")))
    check_dual = {}
    possible_sides = []

    for i in sides:
        if i in check_dual:
            check_dual[i] += 1
        else:
            check_dual[i] = 1

    tmp_square = 0
    for k, v in check_dual.items():
        if v >= 4 and k > tmp_square:
            tmp_square = k
            possible_sides.append(k)
        elif v == 2 or v == 3:
            possible_sides.append(k)
        else:
            pass

    possible_sides.sort(reverse=True)
    if tmp_square == 0 and len(possible_sides) < 2:
        print(0)
    elif tmp_square != 0 and len(possible_sides) == 0:
        print(tmp_square ** 2)
    elif tmp_square != 0 and len(possible_sides) == 1:
        print(max(tmp_square ** 2, tmp_square * possible_sides[0]))
    else:
        print(max(tmp_square ** 2, possible_sides[0] * possible_sides[1]))

solve()